Liquid-discharging device and printing system

ABSTRACT

The present invention relates to a liquid ejecting apparatus including: a movable head provided with a plurality of nozzles for ejecting a liquid; a carry unit for carrying a medium in a predetermined carrying direction; and a sensor for detecting an edge of the medium, the liquid ejecting apparatus controlling ejection of the liquid from the plurality of nozzles in accordance with a result of the detection of the sensor. In this liquid ejecting apparatus, the position, in the carrying direction, of the sensor is at the same position of or on an upstream side of a nozzle located most upstream in the carrying direction, of among the plurality of nozzles. In this way, it is possible to arrange the sensor for detecting the edge of the paper at the most suitable position, and to suppress waste of ink that is ejected from the nozzles.

TECHNICAL FIELD

The present invention relates to liquid ejecting apparatuses andprinting systems.

The present application claims priority upon Japanese Patent ApplicationNo. 2002-217232 filed on Jul. 25, 2002 and Japanese Patent ApplicationNo. 2003-119002 filed on Apr. 23, 2003, the contents of which are hereinincorporated by reference.

BACKGROUND ART

Inkjet printers that perform printing by intermittently ejecting ink(liquid) are known as printing apparatuses (which are also liquidejecting apparatuses) that print images on various types of media suchas paper, cloth, and films. In such inkjet printers, images are printedon media by repeating, in alternation, the step of carrying paper in acarrying direction and the step of ejecting ink while moving nozzles ina scanning direction.

Further, in such printing apparatuses, it is known to provide a sensorfor detecting the edges of the paper on a carriage and to controlejection of ink from the nozzles according to the detection results ofthe sensor.

The present invention has an objective of enabling the sensor fordetecting the edges of the paper to be positioned at the most suitableposition, and suppressing waste of ink ejected from the nozzles.

DISCLOSURE OF INVENTION

The present invention relates to a liquid ejecting apparatus providedwith: a movable head that is provided with a plurality of nozzles forejecting a liquid; a carry unit for carrying a medium in a predeterminedcarrying direction; and a sensor for detecting an edge of the medium,the liquid ejecting apparatus controlling ejection of the liquid fromthe plurality of nozzles in accordance with a result of the detection ofthe sensor. The position, in the carrying direction, of the sensor is atthe same position of or on an upstream side of a nozzle located mostupstream in the carrying direction, of among the plurality of nozzles.Further, due to a detection error in the sensor that occurs when thesensor detects the edge of the medium, a position of the edge of themedium when the edge is detected fluctuates within a range from a firstposition to a second position; and the position, in the carryingdirection, of a nozzle located most upstream in the carrying direction,of among the plurality of nozzles, is between the first position and thesecond position. Further, the position, in the carrying direction, ofthe sensor is on an upstream side of a nozzle located most upstream inthe carrying direction, of among the plurality of nozzles.

It should be noted that it is possible to grasp the present inventionfrom other viewpoints. Other features of the present invention will bemade clear through the description herein and the accompanying drawings.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a block diagram showing the configuration of a printing systemserving as an example of the present invention.

FIG. 2 is a schematic perspective view showing an example of the primarystructures of a color inkjet printer 20.

FIG. 3 is a schematic diagram for describing an example of a reflectiveoptical sensor 29.

FIG. 4 is a diagram showing the configuration of the periphery of acarriage 28 of the inkjet printer.

FIG. 5 is an explanatory diagram that schematically shows theconfiguration of a linear encoder 11 attached to the carriage 28.

FIG. 6A is a timing chart showing the waveforms of the two outputsignals of the linear encoder 11 when the CR motor is rotating forward.FIG. 6B is a timing chart showing the waveforms of the two outputsignals of the linear encoder 11 when the CR motor is rotating inreverse.

FIG. 7 is a block diagram showing an example of the electricalconfiguration of the color inkjet printer 20.

FIG. 8 is an explanatory diagram showing the nozzle arrangement on thebottom surface of the print head 36.

FIG. 9 is a flowchart for describing the first embodiment.

FIG. 10A to FIG. 10C are diagrams that schematically represent thepositional relationship between the nozzles of the print head 36 and theprint paper P.

FIG. 11 is a diagram that schematically represents the positionalrelationship between the nozzles of the print head 36 and the printpaper P.

FIG. 12 is a diagram that schematically represents the positionalrelationship between the nozzles of the print head 36 and the printpaper P.

FIG. 13 is a diagram that schematically represents the positionalrelationship between the nozzles of the print head 36 and the printpaper P.

FIG. 14 is an explanatory diagram showing the external configuration ofthe computer system.

FIG. 15 is a block diagram showing the configuration of the computersystem shown in FIG. 14.

FIG. 16 is an explanatory drawing showing an overall configuration of aprinting system.

FIG. 17 is a block diagram of an overall configuration of a printer.

FIG. 18 is a schematic diagram of the overall configuration of theprinter.

FIG. 19 is lateral sectional view of the overall configuration of theprinter.

FIG. 20 is a flowchart of the processing during printing.

FIG. 21 is a flowchart of the paper supply processing.

FIG. 22A to FIG. 22E are explanatory diagrams showing how the papersupply processing is performed as viewed from the upper surface.

FIG. 23 is a flowchart of the paper-skew correction processing.

FIG. 24A to FIG. 24D are explanatory diagrams of how the paper-skewcorrection processing is performed as viewed from the upper surface.

FIG. 25 is an explanatory diagram of showing the structure of the carryunit.

FIG. 26 is an explanatory diagram of the configuration of the rotaryencoder.

FIG. 27A is a timing chart of the waveforms of the output signals duringforward rotation. FIG. 27B is a timing chart of the waveforms of theoutput signals during reverse rotation.

FIG. 28 is a flowchart of the carrying process.

FIG. 29 is an explanatory diagram showing the arrangement of nozzles.

FIG. 30 is an explanatory diagram of a configuration of the opticalsensor.

FIG. 31 is an explanatory diagram of output signals of the opticalsensor 54.

FIG. 32 is an explanatory diagram of an attachment position of theoptical sensor.

FIG. 33A to FIG. 33D are explanatory diagrams showing how the paper iscarried.

FIG. 34 is an explanatory diagram of borderless printing.

FIG. 35A is an explanatory diagram of detection of the lateral edge ofthe paper. FIG. 35B is an explanatory diagram of the lateral edgeprocessing in borderless printing.

FIG. 36A to FIG. 36C are explanatory diagrams of the rear edgeprocessing of the present embodiment.

FIG. 37A and FIG. 37B are explanatory diagrams of the rear edgeprocessing of a reference example.

REGARDING THE REFERENCE CHARACTERS

-   11 linear encoder-   12 linear encoder code plate-   13 rotary encoder-   20 color inkjet printer-   21 CRT-   22 paper stacker-   24 paper feed roller-   25 pulley-   26 platen-   28 carriage-   29 reflective optical sensor-   30 carriage motor-   31 paper feed motor-   32 pull belt-   34 guide rails-   36 print head-   38 light-emitting section-   40 light-receiving section-   50 buffer memory-   52 image buffer-   54 system controller-   56 main memory-   58 EEPROM-   61 main-scan drive circuit-   62 sub-scan drive circuit-   63 head drive circuit-   65 reflective optical sensor control circuit-   66 electric signal measuring section-   90 computer-   91 video driver-   95 application program-   96 printer driver-   97 resolution conversion module-   98 color conversion module-   99 halftone module-   100 rasterizer-   101 user interface display module-   102 UI printer interface module-   1000 computer system-   1102 main computer unit-   1104 display device-   1106 printer-   1108 input device-   1108A keyboard-   1108B mouse-   1110 reading device-   1110A flexible disk drive device-   1110B CD-ROM drive device-   1202 internal memory-   1204 hard disk drive unit-   201 printer-   220 carry unit-   221 paper supplying roller-   222 carry motor (PF motor)-   223 carry roller-   224 platen-   225 paper discharge roller-   230 carriage unit-   231 carriage-   232 carriage motor (CR motor)-   240 head unit-   241 head-   250 detector group-   251 linear encoder-   252 rotary encoder-   2521 scale-   2522 detector-   253 paper detection sensor-   254 optical sensor-   260 controller-   261 interface section-   262 CPU-   263 memory-   264 unit control circuit-   2100 printing system-   2110 computer-   2120 display device-   2130 input device-   2130A keyboard-   2130B mouse-   2140 record/play device-   2140A flexible disk drive device-   2140B CD-ROM drive device

BEST MODE FOR CARRYING OUT THE INVENTION

Overview of Disclosure

At least the following will be made clear through the disclosure below.

A liquid ejecting apparatus comprises: a movable head that is providedwith a plurality of nozzles for ejecting a liquid; a carry unit forcarrying a medium in a predetermined carrying direction; and a sensorfor detecting an edge of the medium; wherein the liquid ejectingapparatus controls ejection of the liquid from the plurality of nozzlesin accordance with a result of the detection of the sensor; and whereina position, in the carrying direction, of the sensor is at the sameposition of or on an upstream side of a nozzle located most upstream inthe carrying direction, of among the plurality of nozzles.

With such a liquid ejecting apparatus, it is possible to arrange thesensor for detecting the edge of the paper at the most suitableposition, and to suppress waste of ink that is ejected from the nozzles.

A liquid ejecting apparatus comprises: a movable head that is providedwith a plurality of nozzles for ejecting a liquid; a carry unit forcarrying a medium in a predetermined carrying direction; and a sensorfor detecting an edge of the medium; wherein the liquid ejectingapparatus controls ejection of the liquid from the plurality of nozzlesin accordance with a result of the detection of the sensor; wherein, dueto a detection error in the sensor that occurs when the sensor detectsthe edge of the medium, a position of the edge of the medium when theedge is detected fluctuates within a range from a first position to asecond position; and wherein a position, in the carrying direction, of anozzle located most upstream in the carrying direction, of among theplurality of nozzles, is between the first position and the secondposition.

With such a liquid ejecting apparatus, it is possible to achieve aliquid ejecting apparatus in which the nozzle located most upstream inthe carrying direction is arranged at an ideal position.

In this liquid ejecting apparatus, it is preferable that the position,in the carrying direction, of the nozzle located most upstream in thecarrying direction is in the middle of the first position and the secondposition. In this way, it is possible to achieve a liquid ejectingapparatus in which the nozzle located most upstream in the carryingdirection is arranged at a further ideal position.

In this liquid ejecting apparatus, it is preferable that the sensordetects the edge of the medium; and based on a result of this detection,the liquid is kept from being ejected from the nozzle located mostupstream in the carrying direction and nozzles located within apredetermined distance from that nozzle in the carrying direction. Inthis way, it becomes possible to further reduce the amount ofconsumption of the liquid.

In this liquid ejecting apparatus, it is preferable that after thesensor detects the edge of the medium, a process of carrying the mediumin the carrying direction using the carry unit and a process of movingthe head and ejecting the liquid onto the medium are repeated for apredetermined number of times, and then ejection of the liquid onto themedium is ended. In this way, it becomes possible to fill the medium upwith dots.

In this liquid ejecting apparatus, it is preferable that thepredetermined number of times is a plural number of times; and thepredetermined distance in the process of ejecting the liquid onto themedium is increased in correspondence with an increase in an aggregatecarry amount of the medium after the detection of the edge of themedium. In this way, it becomes possible to increase the number ofnozzles that do not eject the liquid in accordance with the increase inthe number of nozzles that do not oppose the medium, and therefore, itis possible to further reduce the amount of consumption of the liquid.

In this liquid ejecting apparatus, it is preferable that thepredetermined distance is a value obtained by subtracting apredetermined amount from the aggregate carry amount. In this way, itbecomes possible to ensure a margin, taking into consideration thedetection error for when the edge of the medium is detected.

In this liquid ejecting apparatus, it is preferable that the higher theprecision of detection with which the edge of the medium is detected is,the smaller the predetermined amount is made. By adjusting the amount ofmargin according to the level of the detection precision in this way, itis possible to determine the nozzles that do not eject ink moreeffectively.

In this liquid ejecting apparatus, it is preferable that the edge of themedium is detected by determining whether or not the edge of the mediumhad passed a predetermining position in the carrying direction. In thisway, it is possible to detect the edge of the medium more reliably.

In this liquid ejecting apparatus, it is preferable that the liquidejecting apparatus further comprises a medium-supporting section forsupporting the medium; the sensor is provided with a light-emittingsection for emitting light toward the medium-supporting section, and alight-receiving section for receiving the light that has been emittedfrom the light-emitting section; and by determining, based on an outputvalue of the light-receiving section, whether or not the medium is in atraveling direction of the light emitted from the light-emittingsection, it is determined whether or not the edge had passed thepredetermined position in the carrying direction. In this way, it ispossible to determine whether or not the edge of the medium has passedthe predetermined position in the carrying direction more easily.

In this liquid ejecting apparatus, it is preferable that the light isemitted from the light-emitting section toward a plurality of positionsdifferent from one another in a direction of movement of the head; andbased on the output value of the light-receiving section that hasreceived the emitted light, it is determined whether or not the mediumis in the traveling direction of the light. In this way, it is possibleto detect the edge of the medium reliably, even when there is a skew inthe medium, for example.

In this liquid ejecting apparatus, it is preferable that the sensor isprovided in/on a movable moving member; the light is emitted from thelight-emitting section toward the plurality of positions while movingthe moving member; and based on the output value of the light-receivingsection that has received the emitted light, it is determined whether ornot the medium is in the traveling direction of the light. In this way,when emitting light from the light-emitting section (light-emittingmeans) toward a plurality of positions different from one another in thescanning direction (main-scanning direction), it is not necessary tochange the direction in which the light is emitted for each of thosepositions.

In this liquid ejecting apparatus, it is preferable that the head isprovided in/on the moving member; and while moving the moving member,the light is emitted from the light-emitting section toward theplurality of positions, based on the output value of the light-receivingsensor that has received the emitted light, it is determined whether ornot the medium is in the traveling direction of the light, and theliquid is ejected from the nozzles provided in the head. In this way, itis possible to use the moving mechanism of the moving member and thelight-emitting section (light-emitting means) and the light-receivingsection (light-receiving sensor) in common.

In this liquid ejecting apparatus, it is preferable that the liquid isejected with respect to an entire surface of the medium. The advantagesof the above-described means become more significant because, in a statewhere a portion of the nozzle face is not in opposition to the medium, asituation in which the liquid is ejected from the nozzles that do notoppose the medium is likely to occur.

In this liquid ejecting apparatus, it is preferable that the liquid isink; and the liquid ejecting apparatus is a printing apparatus thatprints on a medium to be printed, which serves as the medium, byejecting the ink from the nozzles. In this way, it is possible toachieve a printing apparatus that allows for the above-describedeffects.

Further, it is also possible to achieve a liquid ejecting apparatuscomprising: a movable head that is provided with a plurality of nozzlesfor ejecting an ink; a carry unit for carrying a medium to be printed ina predetermined carrying direction; and a sensor for detecting an edgeof the medium to be printed; wherein the liquid ejecting apparatuscontrols ejection of the ink from the plurality of nozzles in accordancewith a result of the detection of the sensor; wherein, due to adetection error in the sensor that occurs when the sensor detects theedge of the medium to be printed, a position of the edge of the mediumto be printed when the edge is detected fluctuates within a range from afirst position to a second position; wherein a position, in the carryingdirection, of a nozzle located most upstream in the carrying direction,of among the plurality of nozzles, is in the middle of the firstposition and the second position; wherein, based on the result of thedetection, the ink is kept from being ejected from the nozzle locatedmost upstream in the carrying direction and nozzles located within apredetermined distance from that nozzle in the carrying direction;wherein, after the sensor detects the edge of the medium to be printed,a process of carrying the medium to be printed in the carrying directionusing the carry unit and a process of moving the head and ejecting theink onto the medium to be printed are repeated for a predeterminednumber of times, and then ejection of the ink onto the medium to beprinted is ended; wherein the predetermined number of times is a pluralnumber of times; wherein the predetermined distance in the process ofejecting the ink onto the medium to be printed is increased incorrespondence with an increase in an aggregate carry amount of themedium to be printed after the detection of the edge of the medium to beprinted; wherein the predetermined distance is a value obtained bysubtracting a predetermined amount from the aggregate carry amount;wherein, the higher the precision of detection with which the edge ofthe medium to be printed is detected is, the smaller the predeterminedamount is made; wherein the edge of the medium to be printed is detectedby determining whether or not the edge of the medium to be printed hadpassed a predetermining position in the carrying direction; wherein theliquid ejecting apparatus further comprises a supporting section forsupporting the medium to be printed; wherein the sensor is provided witha light-emitting section for emitting light toward the supportingsection, and a light-receiving section for receiving the light that hasbeen emitted from the light-emitting section; wherein, by determining,based on an output value of the light-receiving section, whether or notthe medium to be printed is in a traveling direction of the lightemitted from the light-emitting section, it is determined whether or notthe edge had passed the predetermined position in the carryingdirection; wherein the light is emitted from the light-emitting sectiontoward a plurality of positions different from one another in adirection of movement of the head; wherein, based on the output value ofthe light-receiving section that has received the emitted light, it isdetermined whether or not the medium to be printed is in the travelingdirection of the light; wherein the sensor is provided in/on a movablemoving member; wherein the light is emitted from the light-emittingsection toward the plurality of positions while moving the movingmember; wherein, based on the output value of the light-receivingsection that has received the emitted light, it is determined whether ornot the medium to be printed is in the traveling direction of the light;wherein the head is provided in/on the moving member; wherein, whilemoving the moving member, the light is emitted from the light-emittingsection toward the plurality of positions, based on the output value ofthe light-receiving sensor that has received the emitted light, it isdetermined whether or not the medium to be printed is in the travelingdirection of the light, and the ink is ejected from the nozzles providedin the head; wherein the ink is ejected with respect to an entiresurface of the medium to be printed; and wherein the liquid ejectingapparatus is a printing apparatus that prints on the medium to beprinted by ejecting the ink from the nozzles.

With such a liquid ejecting apparatus, the object of the presentinvention is most effectively achieved because all of the effectsdescribed above can be obtained.

Further, a printing system comprises: a main computer unit; and a liquidejecting apparatus that is connectable to the main computer unit andthat is provided with a movable head that is provided with a pluralityof nozzles for ejecting a liquid; a carry unit for carrying a medium ina predetermined carrying direction; and a sensor for detecting an edgeof the medium; wherein the liquid ejecting apparatus controls ejectionof the liquid from the plurality of nozzles in accordance with a resultof the detection of the sensor; and wherein a position, in the carryingdirection, of the sensor is at the same position of or on an upstreamside of a nozzle located most upstream in the carrying direction, ofamong the plurality of nozzles.

As an overall system, the printing system described above is moresuperior to conventional systems.

Further, a liquid ejecting apparatus comprises: a movable head that isprovided with a plurality of nozzles for ejecting a liquid; a carry unitfor carrying a medium in a predetermined carrying direction; and asensor for detecting an edge of the medium and that is movable with thehead; wherein the liquid ejecting apparatus controls ejection of theliquid from the plurality of nozzles in accordance with a result of thedetection of the sensor; and wherein a position, in the carryingdirection, of the sensor is at the same position of or on an upstreamside of a nozzle located most upstream in the carrying direction, ofamong the plurality of nozzles.

With such a liquid ejecting apparatus, it is possible to achieve aliquid ejecting apparatus in which the nozzle located most upstream inthe carrying direction is arranged at a further ideal position.

A liquid ejecting apparatus comprises: a movable head that is providedwith a plurality of nozzles for ejecting a liquid; a carry unit forcarrying a medium in a predetermined carrying direction; and a sensorfor detecting an edge of the medium and that is movable with the head;wherein the liquid ejecting apparatus controls ejection of the liquidfrom the plurality of nozzles in accordance with a result of thedetection of the sensor; and wherein a position, in the carryingdirection, of the sensor is on an upstream side of a nozzle located mostupstream in the carrying direction, of among the plurality of nozzles.

With such a liquid ejecting apparatus, the sensor can detect the frontedge of the medium before the liquid becomes ejectable onto the frontedge of the medium. Further, with such a liquid ejecting apparatus, thesensor can detect the rear edge of the medium before the liquid becomesejectable onto the rear edge of the medium. Further, with such a liquidejecting apparatus, it is possible to detect the lateral edge of themedium with high accuracy because ink has not been ejected onto thedetection region of the sensor.

In this liquid ejecting apparatus, it is preferable that the sensordetects a lateral edge of the medium; and the liquid ejecting apparatuscontrols ejection of the liquid from the plurality of nozzles inaccordance with a position of the lateral edge of the medium that hasbeen detected. Since the sensor is arranged on the upstream side of themost upstream nozzle, the region in which the sensor detects the edge ofthe medium is away from the region in which the liquid is ejected ontothe medium. Therefore, with such a liquid ejecting apparatus, since thesensor detects the lateral edge in a region where the liquid is notejected, it is possible to detect the lateral edge of the medium withhigh accuracy and to control ejection of the liquid in accordance withthe position of the lateral edge with high accuracy.

In this liquid ejecting apparatus, it is preferable that a position, onthe most downstream side in the carrying direction, of a detectionregion of the sensor is located on the upstream side, in the carryingdirection, of the nozzle located most upstream in the carryingdirection. In this way, the entire detection region becomes preferablefor detecting the edge of the medium.

In this liquid ejecting apparatus, it is preferable that the carry unitcarries the medium by a predetermined carry amount in the carryingdirection; and the position, in the carrying direction, of the sensor ison the upstream side, in the carrying direction, away from the nozzlelocated most upstream in the carrying direction by more than the carryamount. Such a liquid ejecting apparatus is suitable for performing rearedge processing.

In this liquid ejecting apparatus, it is preferable that the liquidejecting apparatus ejects the liquid onto the edge of the medium using aportion of the plurality of nozzles after the sensor no longer detectsthe medium. With such a liquid ejecting apparatus, it is possible tolimit the nozzles to be used depending on the detection results of thesensor.

In this liquid ejecting apparatus, it is preferable that the liquidejecting apparatus ejects the liquid onto the medium using all of theplurality of nozzles in a state where the sensor no longer detects themedium, and after the carry unit has further carried the medium by thecarry amount, the liquid ejecting apparatus ejects the liquid onto theedge of the medium using a portion of the plurality of nozzles. Withsuch a liquid ejecting apparatus, there is time for calculating whichnozzles are to be used during the period from when the sensor detectsthe rear edge of the medium up to when printing is performed by limitingthe nozzles used.

In this liquid ejecting apparatus, it is preferable that a position, onthe most downstream side in the carrying direction, of a detectionregion of the sensor is on the upstream side, in the carrying direction,away from the nozzle located most upstream in the carrying direction bymore than the carry amount. With such a liquid ejecting apparatus, theentire detection region becomes preferable for detecting the edge of themedium.

In this liquid ejecting apparatus, it is preferable that the carry unithas a carry roller for carrying the medium up to a position where theliquid can be ejected onto the medium; and the position, in the carryingdirection, of the sensor is on the downstream side of the carry roller.With such a liquid ejecting apparatus the sensor can detect the frontedge of the paper with high accuracy.

In this liquid ejecting apparatus, it is preferable that a process ofcorrecting a skew in the medium is performed on the upstream side of thecarry roller. A slippage occurs between the carry roller and the mediumwhen correcting the skew in the medium. However, with such a liquidejecting apparatus, the front edge of the medium is detected by thesensor after the medium-skew correction processing, and therefore, it ispossible to correctly perform control (for example, positioning to theprint start position) using the detection results of the front edge ofmedium.

In this liquid ejecting apparatus, it is preferable that a position, onthe most upstream side in the carrying direction, of a detection regionof the sensor is on the downstream side, in the carrying direction, ofthe carry roller. In this way, the entire detection region becomespreferable for detecting the edge of the medium.

In this liquid ejecting apparatus, it is preferable that the liquidejecting apparatus further comprises a supporting section for supportingthe medium that is carried from the carry roller; and the sensor isarranged such that a detection region of the sensor is located on thesupporting section. In this way, the sensor will detect the supportingsection if there is no medium.

In this liquid ejecting apparatus, it is preferable that calibration ofthe sensor is performed based on an output signal of the sensor in astate in which the supporting section is not supporting the medium. Inthis way, since it is possible to perform calibration in a preferablestate, it becomes possible to increase the detection precision of thesensor.

In this liquid ejecting apparatus, it is preferable that a position, onthe most upstream side in the carrying direction, of the detectionregion of the sensor is on the supporting section. In this way, theentire detection region becomes preferable for detecting the edge of themedium.

In this liquid ejecting apparatus, it is preferable that the carry unitcarries the medium in a slanted manner with respect to the supportingsection; and the position of the sensor is on the downstream side, inthe carrying direction, of a position at which a front edge of themedium first comes into contact with the supporting section. In thisway, the posture of the medium is stable in the detection region of thesensor, and therefore, it is possible to detect the edge of the paperwith the sensor correctly.

In this liquid ejecting apparatus, it is preferable that the carry unithas a paper discharge roller for discharging the medium; and the mediumthat has been carried in a slanted manner with respect to the supportingsection passes a print region within which the liquid ejected from thenozzles land, and then reaches the paper discharge roller. In this way,it is possible to detect the edge of the paper with the sensorcorrectly, even before the front edge of the paper reaches the paperdischarge roller (i.e., when the front edge of the paper tends to liftup easily).

In this liquid ejecting apparatus, it is preferable that a position, onthe most upstream side in the carrying direction, of the detectionregion of the sensor is on the downstream side, in the carryingdirection, of the position at which the front edge of the medium firstcomes into contact with the supporting section. In this way, the entiredetection region becomes preferable for detecting the edge of themedium.

In this liquid ejecting apparatus, it is preferable that the liquid isink; and the liquid ejecting apparatus is a printing apparatus thatprints on a medium to be printed, which serves as the medium, byejecting the ink from the nozzles. In this way, it is possible toachieve a printing apparatus that allows for the above-describedeffects.

Further, a liquid ejecting apparatus comprises: a movable head that isprovided with a plurality of nozzles for ejecting an ink; a carry unitfor carrying a medium to be printed in a predetermined carryingdirection; and a sensor for detecting an edge of the medium to beprinted and that is movable with the head; wherein the liquid ejectingapparatus controls ejection of the ink from the plurality of nozzles inaccordance with a result of the detection of the sensor; wherein aposition, in the carrying direction, of the sensor is on an upstreamside of a nozzle located most upstream in the carrying direction, ofamong the plurality of nozzles; wherein the sensor detects a lateraledge of the medium to be printed; wherein the liquid ejecting apparatuscontrols ejection of the ink from the plurality of nozzles in accordancewith a position of the lateral edge of the medium to be printed that hasbeen detected; wherein a position, on the most downstream side in thecarrying direction, of a detection region of the sensor is located onthe upstream side, in the carrying direction, of the nozzle located mostupstream in the carrying direction; wherein the carry unit carries themedium to be printed by a predetermined carry amount in the carryingdirection; wherein the position, in the carrying direction, of thesensor is on the upstream side, in the carrying direction, away from thenozzle located most upstream in the carrying direction by more than thecarry amount; wherein the liquid ejecting apparatus ejects the ink ontothe edge of the medium to be printed using a portion of the plurality ofnozzles after the sensor no longer detects the medium to be printed;wherein the liquid ejecting apparatus ejects the ink onto the medium tobe printed using all of the plurality of nozzles in a state where thesensor no longer detects the medium to be printed, and after the carryunit has further carried the medium to be printed by the carry amount,the liquid ejecting apparatus ejects the ink onto the edge of the mediumto be printed using a portion of the plurality of nozzles; wherein theposition, on the most downstream side in the carrying direction, of thedetection region of the sensor is on the upstream side, in the carryingdirection, away from the nozzle located most upstream in the carryingdirection by more than the carry amount; wherein the carry unit has acarry roller for carrying the medium to be printed up to a positionwhere the ink can be ejected onto the medium to be printed; wherein theposition, in the carrying direction, of the sensor is on the downstreamside of the carry roller; wherein a process of correcting a skew in themedium to be printed is performed on the upstream side of the carryroller; wherein a position, on the most upstream side in the carryingdirection, of the detection region of the sensor is on the downstreamside, in the carrying direction, of the carry roller; wherein the liquidejecting apparatus further comprises a supporting section for supportingthe medium to be printed that is carried from the carry roller; whereinthe sensor is arranged such that the detection region of the sensor islocated on the supporting section; wherein calibration of the sensor isperformed based on an output signal of the sensor in a state in whichthe supporting section is not supporting the medium to be printed;wherein the position, on the most upstream side in the carryingdirection, of the detection region of the sensor is on the supportingsection; wherein the carry unit carries the medium to be printed in aslanted manner with respect to the supporting section; wherein theposition of the sensor is on the downstream side, in the carryingdirection, of a position at which a front edge of the medium to beprinted first comes into contact with the supporting section; whereinthe carry unit has a paper discharge roller for discharging the mediumto be printed; wherein the medium to be printed that has been carried ina slanted manner with respect to the supporting section passes a printregion within which the ink ejected from the nozzles land, and thenreaches the paper discharge roller; wherein the position, on the mostupstream side in the carrying direction, of the detection region of thesensor is on the downstream side, in the carrying direction, of theposition at which the front edge of the medium to be printed first comesinto contact with the supporting section; and wherein the liquidejecting apparatus is a printing apparatus that prints on the medium tobe printed by ejecting the ink from the nozzles.

With such a liquid ejecting apparatus, it is possible to achieve theeffects described above.

Further, a printing system comprises: a main computer unit; and a liquidejecting apparatus that is connectable to the main computer unit andthat is provided with a movable head that is provided with-a pluralityof nozzles for ejecting a liquid; a carry unit for carrying a medium ina predetermined carrying direction; and a sensor for detecting an edgeof the medium and that is movable with the head; wherein the liquidejecting apparatus controls ejection of the liquid from the plurality ofnozzles in accordance with a result of the detection of the sensor; andwherein a position, in the carrying direction, of the sensor is on anupstream side of a nozzle located most upstream in the carryingdirection, of among the plurality of nozzles.

As an overall system, the printing system described above is moresuperior to conventional systems.

(1)

(1) EXAMPLE OF THE OVERALL CONFIGURATION OF THE APPARATUS

FIG. 1 is a block diagram showing the configuration of a printing systemserving as an example of the present invention. The printing system isprovided with a computer 90 and a color inkjet printer 20, which is anexample of a liquid ejecting apparatus. It should be noted that theprinting system including the color inkjet printer 20 and the computer90 can also be broadly referred to as a “liquid ejecting apparatus.”Although not shown in the diagram, a computer system is made of thecomputer 90, the color inkjet printer 20, a display device such as a CRT21 or a liquid crystal display device, input devices such as a keyboardand a mouse, and a drive device such as a flexible drive device or aCD-ROM drive device.

In the computer 90, an application program 95 is executed under apredetermined operating system. The operating system includes a videodriver 91 and a printer driver 96, and the application program 95outputs print data PD for transfer to the color inkjet printer 20through these drivers. The application program 95, which carries outretouching of images, for example, carries out a desired process withrespect to an image to be processed, and also displays the image on theCRT 21 via the video driver 91.

When the application program 95 issues a print command, the printerdriver 96 of the computer 90 receives image data from the applicationprogram 95 and converts these into print data PD to be supplied to thecolor inkjet printer 20. The printer driver 96 is internally providedwith a resolution conversion module 97, a color conversion module 98, ahalftone module 99, a rasterizer 100, a user interface display module101, a UI printer interface module 102, and a color conversion look-uptable LUT.

The resolution conversion module 97 performs the function of convertingthe resolution of the color image data formed by the application program95 to a print resolution. The image data whose resolution is thusconverted is image information still made of the three color componentsRGB. The color conversion module 98 refers to the color conversionlook-up table LUT and, for each pixel, converts the RGB image data intomulti-gradation data of a plurality of ink colors that can be used bythe color inkjet printer 20.

The multi-gradation data that have been color converted have a gradationvalue of 256 grades, for example. The halftone module 99 executesso-called halftone processing to create halftone image data. Thehalftone image data are arranged by the rasterizer 100 into the order inwhich they are to be transferred to the color inkjet printer 20, and areoutput as the final print data PD. The print data PD include raster dataindicating the state in which dots are formed during main scanning, anddata indicating the sub-scan feed amount (carry amount).

The user interface display module 101 has a function for displayingvarious types of user interface windows related to printing and afunction for receiving input from the user in these windows.

The UI printer interface module 102 functions as an interface betweenthe user interface (UI) and the color inkjet printer. It interpretsinstructions given by users through the user interface and sends variouscommands COM to the color inkjet printer. Conversely, it also interpretscommands COM received from the color inkjet printer and executes variousdisplays with respect to the user interface.

It should be noted that the printer driver 96 realizes, for example, afunction for sending and receiving various types of commands COM and afunction for supplying print data PD to the color inkjet printer 20. Aprogram for realizing the functions of the printer driver 96 is suppliedin a format in which it is stored on a computer-readable storage medium.Examples of this storage medium include various types ofcomputer-readable media, such as flexible disks, CD-ROMs, magnetooptical disks, IC cards, ROM cartridges, punch cards, printed materialson which a code such as a bar code is printed, internal storage devices(memory such as a RAM or a ROM) and external storage devices of thecomputer. The computer program can also be downloaded onto the computer90 via the Internet.

FIG. 2 is a schematic perspective view showing an example of the primarystructures of the color inkjet printer 20. The color inkjet printer 20is provided with a paper stacker 22, a paper feed roller 24 driven by astep motor that is not shown, a platen 26, which is an example of amedium-supporting section for supporting the medium, a carriage 28serving as an example of a moving member, a carriage motor 30, a pullbelt 32 that is driven by the carriage motor 30, and guide rails 34 forthe carriage 28. Further, a print head 36, which is an example of anejection head provided with numerous nozzles, and a reflective opticalsensor 29 that serves as an example of detecting means (sensing means)and that will be described in detail later are mounted onto the carriage28.

The print paper P is rolled from the paper stacker 22 by the paper feedroller 24 and fed in a paper-feed direction (hereinafter also referredto as the sub-scanning direction and the carrying direction), which isan example of the predetermined feed direction, over the surface of theplaten 26. The carriage 28 is pulled by the pull belt 32, which isdriven by the carriage motor 30, and moves in the main-scanningdirection along the guide rails 34. It should be noted that as shown inthe diagram, the main-scanning direction (also referred to simply as thescanning direction) refers to the two directions perpendicular to thesub-scanning direction. The paper feed roller 24 is also used to carryout the paper-supply operation for supplying the print paper P to thecolor inkjet printer 20 and the paper discharge operation fordischarging the print paper P from the color inkjet printer 20.

(1) EXAMPLE OF CONFIGURATION OF THE REFLECTIVE OPTICAL SENSOR

FIG. 3 is a schematic diagram for describing an example of thereflective optical sensor 29. The reflective optical sensor 29 isattached to the carriage 28, and has a light-emitting section 38, whichis for example made of a light emitting diode and is an example of alight-emitting means, and a light-receiving section 40, which is forexample made of a phototransistor and is an example of a light-receivingsensor. The light that is emitted from the light-emitting section 38,that is, the incident light, is reflected by print paper P or by theplaten 26 if there is no print paper P in the direction in which theemitted light travels. The light that is reflected is received by thelight-receiving section 40 and is converted into an electric signal.Then, the magnitude of the electric signal is measured as the outputvalue of the light-receiving sensor corresponding to the intensity ofthe reflected light that is received.

It should be noted that in the above description, as shown in thefigure, the light-emitting section 38 and the light-receiving section 40are provided as a single unit and together constitute the reflectiveoptical sensor 29. However, they may also constitute separate devices,such as a light emitting device and a light-receiving device.

Further, in the above description, the reflected light was convertedinto an electric signal and then the magnitude of that electric signalwas measured in order to obtain the intensity of the reflected lightthat is received. However, this is not a limitation, and it is onlynecessary that the output value of the light-receiving sensorcorresponding to the intensity of the reflected light that is receivedcan be measured.

(1) EXAMPLE OF CONFIGURATION OF THE PERIPHERY OF THE CARRIAGE

The configuration of the carriage area is described next. FIG. 4 is adiagram showing the configuration of the periphery of the carriage 28 ofthe inkjet printer.

The inkjet printer shown in FIG. 4 is provided with a paper feed motor(hereinafter referred to as PF motor) 31, which is as an example of thefeed mechanism for feeding paper, the carriage 28 to which the printhead 36 for ejecting ink, which is an example of a liquid, onto theprint paper P is fastened and which is driven in the main-scanningdirection, the carriage motor (hereinafter referred to as CR motor) 30for driving the carriage 28, a linear encoder 11 that is fastened to thecarriage 28, a linear encoder code plate 12 in which slits are formed ata predetermined spacing, a rotary encoder 13, which is not shown, forthe PF motor 31, the platen 26 for supporting the print paper P, thepaper feed roller 24 driven by the PF motor 31 for carrying the printpaper P, a pulley 25 attached to the rotational shaft of the CR motor30, and the pull belt 32 driven by the pulley 25. It should be notedthat the paper feed roller 24 and the paper feed motor 31 structure apart of the carry unit for carrying the paper.

Next, the above-described linear encoder 11 and the rotary encoder 13are described. FIG. 5 is an explanatory diagram that schematically showsthe configuration of the linear encoder 11 attached to the carriage 28.

The linear encoder 11 shown in FIG. 5 is provided with a light emittingdiode 11 a, a collimating lens 11 b, and a detection processing section11 c. The detection processing section 11 c has a plurality of (forexample, four) photodiodes 11 d, a signal processing circuit 11 e, andfor example two comparators 11 fA and 11 fB.

The light-emitting diode 11 a emits light when a voltage Vcc is appliedto it via resistors on both sides. This light is condensed into parallellight by the collimating lens 11 b and passes through the linear encodercode plate 12. The linear encoder code plate 12 is provided with slitsat a predetermined spacing (for example, 1/180 inch (one inch=2.54 cm)).

The parallel light that passes through the linear encoder code plate 12then passes through stationary slits which are not shown and is incidenton the photodiodes 11 d, where it is converted into electric signals.The electric signals that are output from the four photodiodes 11 d aresubjected to signal processing by the signal processing circuit 11 e,the signals that are output from the signal processing circuit 11 e arecompared in the comparators 11 fA and 11 fB, and the results of thesecomparisons are output as pulses. Then, the pulse ENC-A and the pulseENC-B that are output from the comparators 11 fA and 11 fB become theoutput of the linear encoder 11.

FIG. 6A is a timing chart showing the waveforms of the two outputsignals of the linear encoder 11 when the CR motor is rotating forward.FIG. 6B is a timing chart showing the waveforms of the two outputsignals of the linear encoder 11 when the CR motor is rotating inreverse.

As shown in FIG. 6A and FIG. 6B, the phases of the pulse ENC-A and thepulse ENC-B are misaligned by 90 degrees both when the CR motor isrotating forward and when it is rotating in reverse. When the CR motor30 is rotating forward, that is, when the carriage 28 is moving in themain-scanning direction, then, as shown in FIG. 6A, the phase of thepulse ENC-A leads the phase of the pulse ENC-B by 90 degrees. On theother hand, when the CR motor 30 is rotating in reverse, then, as shownin FIG. 6B, the phase of the pulse ENC-A is delayed by 90 degrees withrespect to the phase of the pulse ENC-B. A single period T of the pulseENC-A and the pulse ENC-B is equivalent to the time during which thecarriage 28 is moved by the slit spacing of the linear encoder codeplate 12.

Then, the rising edge and the rising edge of the output pulses ENC-A andENC-B of the linear encoder 11 are detected, and the number of detectededges is counted. The rotational position of the CR motor 30 is detectedbased on the number that is calculated. With respect to the calculation,when the CR motor 30 is rotating forward a “+1” is added for eachdetected edge, and when the CR motor 30 is rotating in reverse a “−1” isadded for each detected edge. The period of the pulses ENC-A and ENC-Bis equal to the time from when one slit of the linear encoder code plate12 passes through the linear encoder 11 to when the next slit passesthrough the linear encoder 11, and the phases of the pulse ENC-A and thepulse ENC-B are misaligned by 90 degrees. Accordingly, a count number of“1” of the calculation corresponds to ¼ of the slit spacing of thelinear encoder code plate 12. Therefore, if the counted number ismultiplied by ¼ of the slit spacing, then the amount that the CR motor30 has moved from the rotational position corresponding to the countnumber “0” can be obtained based on this product. The resolution of thelinear encoder 11 at this time is ¼ the slit spacing of the linearencoder code plate 12.

On the other hand, the rotary encoder 13 for the PF motor 31 has thesame configuration as the linear encoder 11, except that the rotaryencoder code plate is a rotation disk that rotates in conjunction withrotation of the PF motor 31. The rotary encoder 13 outputs two outputpulses ENC-A and ENC-B, and based on this output the amount of movementof the PF motor 31 can be obtained.

(1) EXAMPLE OF THE ELECTRIC CONFIGURATION OF THE COLOR INKJET PRINTER

FIG. 7 is a block diagram showing an example of the electricconfiguration of the color inkjet printer 20. The color inkjet printer20 is provided with a buffer memory 50 for receiving signals suppliedfrom the computer 90, an image buffer 52 for storing print data, asystem controller 54 for controlling the overall operation of the colorinkjet printer 20, a main memory 56, and an EEPROM 58. The systemcontroller 54 is connected to a main-scan drive circuit 61 for drivingthe carriage motor 30, a sub-scan drive circuit 62 for driving the paperfeed motor 31, a head drive circuit 63 for driving the print head 36, areflective optical sensor control circuit 65 for controlling thelight-emitting section 38 and the light-receiving section 40 of thereflective optical sensor 29, the above-described linear encoder 11, andthe above-described rotary encoder 13. Further, the reflective opticalsensor control circuit 65 is provided with an electric signal measuringsection 66 for measuring the electric signals that are converted fromthe reflected light received by the light-receiving section 40.

The print data that are transferred from the computer 90 are heldtemporarily in the buffer memory 50. Within the color inkjet printer 20,the system controller 54 reads necessary information from the print datain the buffer memory 50, and based on this information, sends controlsignals to the main-scan drive circuit 61, the sub-scan drive circuit62, and the head drive circuit 63, for example.

The image buffer 52 stores print data for a plurality of colorcomponents that are received by the buffer memory 50. The head drivecircuit 63 reads the print data of the various color components from theimage buffer 52 in accordance with the control signals from the systemcontroller 54, and drives the various color nozzle arrays provided inthe print head 36 in correspondence with the print data.

(1) EXAMPLE OF NOZZLE ARRANGEMENT OF PRINT HEAD, ETC.

FIG. 8 is an explanatory diagram showing the nozzle arrangement on thebottom surface of the print head 36. The print head 36 has a blacknozzle row, a yellow nozzle row, a magenta nozzle row, and a cyan nozzlerow, arranged in straight lines in the sub-scanning direction. As shownin the diagram, each of these nozzle rows is constituted by two rows,and in this specification, these nozzle rows are referred to as thefirst black nozzle row, the second black nozzle row, the first yellownozzle row, the second yellow nozzle row, the first magenta nozzle row,the second magenta nozzle row, the first cyan nozzle row, and the secondcyan nozzle row.

The black nozzle rows (shown by white circles) have 360 nozzles, nozzles#1 to #360 of these nozzles, the odd-numbered nozzles #1, #3, . . . ,#359 belong to the first black nozzle row and the even-numbered nozzles#2, #4, . . . , #360 belong to the second black nozzle row. The nozzles#1, #3, . . . , #359 of the first black nozzle row are arranged at aconstant nozzle pitch k·D in the sub-scanning direction. Here, D is thedot pitch in the sub-scanning direction, and k is an integer. The dotpitch D in the sub-scanning direction is equal to the pitch of the mainscan lines (raster lines). Hereafter, the integer k indicating thenozzle pitch k·D is referred to simply as the “nozzle pitch k.” In theexample of FIG. 8, the nozzle pitch k is four dots. The nozzle pitch k,however, may be set to any integer.

The nozzles #2, #4, . . . , #360 of the second black nozzle row are alsoarranged at the constant nozzle pitch k·D (nozzle pitch k=4) in thesub-scanning direction, and as shown in the diagram, the positions ofthe nozzles in the sub-scanning direction are misaligned with thepositions of the nozzles of the first black nozzle row in thesub-scanning direction. In the example of FIG. 8, the amount of thismisalignment is ½·k·D (k=4).

The above-described matters also apply for the yellow nozzle rows (shownby white triangles), the magenta nozzle rows (shown by white squares),and the cyan nozzle rows (shown by white diamonds). In other words, eachof the these nozzle rows has 360 nozzles #1 to #360, and of the thesenozzles, the odd-numbered nozzles #1, #3, . . . , #359 belong to thefirst nozzle row and the even-numbered nozzles #2, #4, . . . , #360belong to the second nozzle row. Further, each of these nozzle rows isarranged at a constant nozzle pitch k·D in the sub-scanning direction,and the positions of the nozzles of the second rows in the sub-scanningdirection are misaligned with the positions of the nozzles of the firstrows in the sub-scanning direction by ½·k·D (k=4).

In other words, the nozzle groups arranged in the print head 36 arestaggered, and during printing, ink droplets are ejected from each ofthe nozzles while the print head 36 is moved in the main-scanningdirection at a constant velocity together with the carriage 28. However,depending on the print mode, not all of the nozzles are always used, andthere are instances in which only some of the nozzles are used.

It should be noted that the reflective optical sensor 29 described aboveis attached to the carriage 28 with the print head 36. Further, in thepresent embodiment, as shown in the figure, the reflective opticalsensor 29 is provided aligned in the main-scanning direction with thenozzle located most upstream, in the paper-feed direction, of among theplurality of nozzles provided in the print head 36.

(1) First Embodiment

Next, a first embodiment of the present invention is described usingFIG. 9 and FIG. 10. FIG. 9 is a flowchart for describing the firstembodiment. FIG. 10 will be described later.

First, the user makes a command to perform printing through theapplication program 95 or the like (step S2). The application program 95receives this instruction and issues a print command, at which time theprinter driver 96 of the computer 90 receives image data from theapplication program 95 and converts them to print data PD includingraster data indicating the state in which dots are formed during mainscanning and data indicating the sub-scan feed amount (carry amount).Moreover, the printer driver 96 supplies the print data PD to the colorinkjet printer 20 together with various commands COM. The color inkjetprinter 20 receives these at its buffer memory 50, after which it sendsthem to the image buffer 52 or the system controller 54.

The user can also designate the size of the print paper P or issue acommand to perform borderless printing to the user interface displaymodule 101. This instruction by the user is received by the userinterface display module 101 and sent to the UI printer interface module102. The UI printer interface module 102 interprets the instruction thathas been given, and sends a command COM to the color inkjet printer 20.The color inkjet printer 20 receives the command COM at the buffermemory 50 and then transmits it to the system controller 54.

The color inkjet printer 20 then drives, for example, the paper feedmotor 31 by the sub-scan drive circuit 62 based on the command that issent to the system controller 54 so as to supply the print paper P (stepS4).

Then, the system controller 54 moves the carriage 28 in themain-scanning direction as it feeds the print paper P in the paper-feeddirection, and ejects ink from the print head 36 provided in thecarriage 28, thereby carrying out borderless printing (step S6, stepS8). It should be noted that the print paper P is fed in the paper-feeddirection by driving the paper feed motor 31 with the sub-scan drivecircuit 62, the carriage 28 is moved in the main-scanning direction bydriving the carriage motor 30 with the main-scan drive circuit 61, andink is ejected from the print head 36 by driving the print head 36 withthe head drive circuit 63.

The color inkjet printer 20 carries out the operations of step S6 andstep S8 in sequence, and if, for example, the number of times thecarriage 28 is moved in the main-scanning direction reaches apredetermined number of times (step S10), then, from the next move ofthe carriage 28 in the main-scanning direction, the following operationis performed.

The system controller 54 controls the reflective optical sensor 29,which is provided in the carriage 28, by the reflective optical sensorcontrol circuit 65, so that light is emitted toward the platen 26 fromthe light-emitting section 38 of the reflective optical sensor 29 (stepS12). The system controller 54 moves the carriage 28 in themain-scanning direction and ejects ink from the print head 36 providedin the carriage 28 so as to perform borderless printing, as well asemits light from the light-emitting section 38 toward a predeterminedposition on the platen 26 in the paper-feed direction but in a pluralityof different positions on the platen 26 in the main-scanning direction,and based on the output values of the light-receiving section 40, whichreceives the light that has been emitted, detects whether or not theprint paper P is in the traveling direction of the light (step S14).

It should be noted that as described above, in this embodiment, thereflective optical sensor 29 is aligned, in the main-scanning direction,with the nozzle located most upstream in the paper-feed direction, ofamong the plurality of nozzles provided in the print head 36. Thus, thepredetermined position, in the paper-feed direction, of the reflectiveoptical sensor 29 corresponds to the position of the nozzle #360 in thepaper-feed direction.

Further, in this embodiment, whether or not the print paper P is in thetraveling direction of the light is always detected while the carriage28 is moving in the main-scanning direction. That is, when the edge ofthe print paper P blocks the light that is emitted from thelight-emitting section 38, the object on which the light that is emittedfrom the light-emitting section 38 is incident changes from the platen26 to the print paper P, and thus the intensity of the electric signal,that is, the value output by the light-receiving section 40 of thereflective optical sensor 29 that receives the light that is reflectedis changed. Then, by measuring the intensity of this electric signalwith the electric signal measuring section 66, the fact that the edge ofthe print paper P has passed the light is detected.

When movement of the carriage 28 in step S14 is over, whether or not theprint paper P was in the traveling direction of the light duringmovement of the carriage 28 in the main-scanning direction is determinedbased on the output value of the light-receiving section 40 (step S16).That is, by determining whether or not the edge of the print paper P onthe upstream side in the paper-feed direction (hereinafter, this edgemay also be referred to as the bottom edge or the rear edge) has passedthe predetermined position in the paper-feed direction (in thisembodiment, the position in the paper-feed direction of the nozzle#360), the portion of the print paper P located on the upstream side inthe paper-feed direction is detected.

If the result of the determination of step S16 is that the print paper Pwas in the traveling direction of the light, then after the print paperP is fed in the paper-feed direction (step S18), the procedure returnsto step S14, and the system controller 54 repeats the above-describedoperations of step S14 through step S18 until the print paper P is nolonger in the traveling direction of the light.

If the result of the determination of step S16 is that the print paper Pwas not in the traveling direction of the light, then the systemcontroller 54 performs the following operation.

A more detailed description is provided using FIG. 10. FIG. 10 showsdiagrams that schematically represent the positional relationshipbetween the nozzles of the print head 36 and the print paper P.

In FIGS. 10A to 10C, the small rectangles shown on the left representthe nozzles of the print head 36. The numbers within the rectangles arethe nozzle numbers, and correspond to the nozzle numbers shown in FIG.8. It should be noted that in FIG. 10A to FIG. 10C, for the sake ofsimplifying the description, only the black nozzle row is shown, andmoreover, the first black nozzle row and the second black nozzle rowshown in FIG. 8 are shown on the same straight line. In FIGS. 10A to10C, the circle shown to the right of nozzle #360 represents thereflective optical sensor 29. As described above, the position of thereflective optical sensor 29 in the paper-feed direction is identical tothe position of the nozzle #360 in the paper-feed direction. Further, aportion of the print paper P (lower right edge) is shown to the right ofthe black nozzle row.

First, let us look at FIG. 10A. FIG. 10A represents the positionalrelationship between the nozzles of the print head 36 and the printpaper P when the above-described operations of step S14 through step S18are repeated and in step S16 it is determined that the print paper P hasnot arrived in the traveling direction of the light. It is clear fromthe diagram that the print paper P has not arrived in the travelingdirection of the light that is emitted from the light-emitting section38 of the reflective optical sensor 29 as the carriage 28, which isprovided with the print head 36 and the reflective optical sensor 29, ismoved in the main-scanning direction (in this embodiment, the directionof the arrow from left to right in the diagram).

In this manner, if the result of the determination of step S16 is thatthe print paper P has not arrived in the traveling direction of thelight, then the system controller 54 feeds the print paper P in thepaper-feed direction as shown in FIG. 10A and FIG. 10B (step S20). Inthis embodiment, the system controller 54 feeds the print paper P by25·D (D is the dot pitch) using a carry roller etc.

Next, the system controller 54 moves the carriage 28 in themain-scanning direction (in this embodiment, the direction of the arrowfrom left to right in FIG. 10B) and ink is ejected from the nozzles ofthe print head 36 provided in the carriage 28 so as to performborderless printing (step S24). During this printing, however, of amongthe plurality of nozzles of the print head 36, the system controller 54does not allow ink to be ejected from the nozzles located on theupstream side in the paper-feed direction. In this embodiment, ink iskept from being ejected from the nozzle located most upstream in thepaper-feed direction and the nozzles within a predetermined distancefrom that nozzle in the paper-feed direction, and in FIG. 10B thesenozzles are the nozzles #353 to #360, shown by rectangles drawn withdashed lines.

It can be understood from the above that a procedure (step S22) fordetermining the nozzles to be kept from ejecting ink is necessary beforeborderless printing is performed by ejecting ink from the nozzles of theprint head 36 (step S24). A specific method for determining whichnozzles are kept from ejecting ink is discussed later.

Next, as shown in FIG. 10B and FIG. 10C, the system controller 54further feeds the print paper P in the paper-feed direction (step S20).In this embodiment, here also, the system controller 54 feeds the printpaper P by 25·D (D is the dot pitch).

Then, the system controller 54 moves the carriage 28 in themain-scanning direction (in this embodiment, the direction of the arrow,from left to right in FIG. 10B) and ink is ejected from the nozzles ofthe print head 36 provided in the carriage 28 so as to performborderless printing (step S24). In this printing as well, of among theplurality of nozzles of the print head 36, the system controller 54 doesnot allow ink to be ejected from the nozzles positioned on the upstreamside in the paper-feed direction. In this embodiment, ink is kept frombeing ejected from the nozzle located most upstream in the paper-feeddirection and the nozzles within a predetermined distance from thatnozzle in the paper-feed direction, and in FIG. 10C these nozzlescorrespond to the nozzles #340 to #360, which are shown by rectanglesdrawn with dashed lines. The nozzles from which ink is not ejected aredetermined prior to step S24 (step S22).

After the above procedure, that is, the procedure from step S20 to S24,has been repeated a predetermined number of times (in FIG. 9, N is thenumber of times), printing of the print paper P is ended (step S26). Theprint paper P is then discharged by the paper feed motor 31, which isdriven by the sub-scan drive circuit 62 (step S28). It should be notedthat since it is necessary to completely fill the print paper P withdots, the predetermined number of times N is determined based on theabove-mentioned nozzle pitch k, whether or not a so-called overlaprecording method is used, and the number of nozzles for recording dotgroups on the same main-scan line if overlap recording is used, forexample.

It should be noted a program for performing the above processes isstored in the EEPROM 58, and the system controller 54 executed theprogram. The system controller 54 controls the motors etc. in theprinter according to the program to achieve the above-describedprocesses.

It should be noted that in the description above, a reflective-typeoptical sensor is used, but this is not a limitation. For example, it ispossible to arrange the light-emitting section and the light-receivingsection such that they oppose one another in a direction perpendicularto both the main-scanning direction and the sub-scanning direction andsuch that they sandwich the print paper therebetween.

Further, in the description above, detection of whether the edge of theprint paper passed the light is started after the number of times thecarriage 28 is moved in the main-scanning direction has reached apredetermined number of times in step S10. This, however, is not alimitation. For example, it is possible to start detection from thefirst movement of the carriage 28 in the main-scanning direction, or tofind an ideal detection timing through calculation etc. to make thenumber of times of detections minimum.

Further, in the description above, the nozzles that do not eject ink aredetermined every time the procedure passes step S22 in the loop fromstep S20 to step S26, but it is possible to determine the nozzles forthe first through N-th times in the step S22 that is performed for thefirst time.

(1) METHOD FOR DETERMINING NOZZLES KEPT FROM EJECTING INK

As described above, the nozzles kept from ejecting ink are determined instep S22. Here, an example of the method for determining these nozzlesis described using FIG. 9 and FIG. 10A to FIG. 10C.

First, as has been mentioned already, in this embodiment the nozzlesthat do not eject ink are the nozzle located most upstream in thepaper-feed direction and the nozzles that are within a predetermineddistance in the paper-feed direction from that nozzle. That is, in theexample of FIG. 10, these are the nozzle #360 and the nozzles within apredetermined distance in the paper-feed direction from nozzle #360.

The predetermined distance is described below. The predetermineddistance is set large to correspond to the increase in the aggregatepaper feed amount (aggregate carry amount) of the print paper P afterthe portion of the print paper P positioned on the upstream side in thepaper-feed direction is detected. More specifically, the predetermineddistance is the amount obtained by subtracting a predetermined amountfrom the aggregate paper feed amount of the print paper P after theportion of the print paper P positioned on the upstream side in thepaper-feed direction is detected. The aggregate paper feed amount in theexample of FIG. 10B is 25·D (D is the dot pitch), and in the example ofFIG. 10C is (25·D+25·D).

The predetermined amount is determined in correspondence with thedetection precision with which the portion of the print paper P on theupstream side in the paper-feed direction is detected. If thepredetermined distance were simply set to the aggregate paper feedamount, then there is no problem if the portion of the print paper P onthe upstream side in the paper-feed direction can be detectedaccurately. However, if it cannot be detected accurately, a situationmay occur in which nozzles that are kept from ejecting ink come intoopposition to the print paper P. The predetermined amount is set so asto avoid this problem and ensure a certain margin. Consequently, thepredetermined amount is made smaller, the higher the detection precisionwith which the portion of the print paper P located on the upstream sidein the paper-feed direction is detected. In the examples of FIGS. 10Band 10C, the predetermined amount is set to an amount of 10·D.

When the above method is employed in the examples of FIG. 10B and FIG.10C, the nozzles that do not eject ink are as follows.

In the example of FIG. 10B, the aggregate paper feed amount is 25·D andthe predetermined amount is 10·D. Consequently, the predetermineddistance is 15·D. The nozzles to be found are nozzle #360 and thenozzles that are within the range of the predetermined distance fromnozzle #360 in the paper-feed direction, and these nozzles are nozzles#353 to #360. It should be noted that the distance in the paper-feeddirection from nozzle #360 to nozzle #353 is a distance of 14·D.

In the example of FIG. 10C, the aggregate paper feed amount is 50·D andthe predetermined amount is 10·D. Consequently, the predetermineddistance is 40·D. The nozzles to be found are nozzle #360 and thenozzles that are within the range of the predetermined distance fromnozzle #360 in the paper-feed direction, and these nozzles are nozzles#340 to #360. It should be noted that the distance in the paper-feeddirection from nozzle #360 to nozzle #340 is a distance of 40·D.

As described earlier, the procedure from step S20 to step S24 shown inFIG. 9 is repeated for a predetermined number of times (in FIG. 9, N isthis number of times). Consequently, step S22 is repeated N number oftimes. The examples of FIG. 10B and FIG. 10C mentioned above fordetermining the nozzles to be kept from ejecting ink are examples inwhich the nozzles are determined the first and the second time,respectively, when step S22 is performed. The same method can also beused to determine the nozzles in the third time through N-th time thatstep S22 is performed.

(1) REGARDING THE DETECTION ERROR FOR WHEN DETECTING THE PORTION OFPRINT PAPER LOCATED ON UPSTREAM SIDE IN PAPER-FEED DIRECTION

Next, consideration is given to a detection error for when detecting theportion of the print paper located on the upstream side in thepaper-feed direction. As described above, the portion of the print paperP located on the upstream side in the paper-feed direction is detectedby determining whether or not the lower edge of the print paper P haspassed a predetermined position in the paper-feed direction (in thisembodiment, the position in the paper-feed direction of the nozzle#360). During this detection, however, detection error occurs.

This is described using FIG. 11. FIG. 11 is a diagram that schematicallyrepresents the positional relationship between the nozzles of the printhead 36 and the print paper P.

In FIG. 11, the small rectangles shown on the left represent the nozzlesof the print head 36. The numbers within the rectangles are the nozzlenumbers, and correspond to the nozzle numbers shown in FIG. 8. It shouldbe noted that in FIG. 11, for the sake of simplifying the description,only the black nozzle row is shown, and moreover, the first black nozzlerow and the second black nozzle row shown in FIG. 8 are represented bythe same straight line.

In FIG. 11, the circle shown to the right of nozzle #360 represents thereflective optical sensor 29. As mentioned above, the position of thereflective optical sensor 29 in the paper-feed direction is identical tothe position of the nozzle #360 in the paper-feed direction. Further, aportion of the print paper P (lower right edge) is shown to the right ofthe black nozzle row. In FIG. 11, two positions of the print paper P areshown; as regards the print paper P shown on the downstream side in thepaper-feed direction, its lower edge position (which is also referred tobelow as the first position) is located more on the downstream side, inthe paper-feed direction, than the reflective optical sensor 29 by adistance of 9·D. On the other hand, as regards the print paper P shownon the upstream side in the paper-feed direction, its lower edgeposition (which is also referred to below as the second position) islocated more on the upstream side, in the paper-feed direction, than thereflective optical sensor 29 by a distance of 9·D.

As described above, a detection error occurs when detecting the portionof the print paper P located on the upstream side in the paper-feeddirection. Due to this detection error, the lower edge position of theprint paper P for when the portion located on the upstream side in thepaper-feed direction has been detected fluctuates between a range fromthe first position to the second position. That is, there is apossibility that the portion of the print paper P located on theupstream side in the paper-feed direction is not detected even when thelower edge position of the print paper P is at position somewhere on theupstream side of the first position, or conversely, the portion of theprint paper P located on the upstream side in the paper-feed directionis detected even when the lower edge position of the print paper P is ata position somewhere on the downstream side of the second position.

Further, as shown in FIG. 11, according to the present embodiment, theposition, in the paper-feed direction, of the nozzle located mostupstream in the paper-feed direction (i.e., the nozzle #360) is on theupstream side of the first position and on the downstream side of thesecond position, and further, is in the middle of the first position andthe second position.

The following advantages can be achieved by providing the position, inthe paper-feed direction, of the nozzle located most upstream in thepaper-feed direction (i.e., the nozzle #360) on the upstream side of thefirst position and on the downstream side of the second position.

These are described using FIG. 12 and FIG. 13. FIG. 12 and FIG. 13 arediagrams that schematically represent the positional relationshipbetween the nozzles of the print head 36 and the print paper P. FIG. 12and FIG. 13 correspond to the drawing of FIG. 11, but the positionalrelationship between the first position or the second position and theposition, in the paper-feed direction, of the nozzle located mostupstream in the paper-feed direction (i.e., the nozzle #360) isdifferent from FIG. 11.

First, attention is paid to FIG. 12. In the example of FIG. 12, theposition, in the paper-feed direction, of the nozzle located mostupstream in the paper-feed direction (i.e., the nozzle #360) is on theupstream side of both the first position and the second position. Thatis, the position in the paper-feed direction of the nozzle #360 isalways on the upstream side of the lower edge position of the printpaper P when detecting the portion of the print paper P located on theupstream side in the paper-feed direction, regardless of theabove-described fluctuation due to the detection error in the lower edgeposition of the print paper P.

If the above-described method for keeping the nozzles positioned on theupstream side of the paper-feed direction from ejecting ink is appliedto this example, then, compared to the example of FIG. 11 for example,the number of nozzles that eject ink, even though they are not requiredto eject ink because they do not oppose the print paper, increases. Thisincrease in the number of nozzles gives rise to a problem that ink isuselessly wasted.

Next, attention is paid to FIG. 13. In the example of FIG. 13, theposition, in the paper-feed direction, of the nozzle located mostupstream in the paper-feed direction (i.e., the nozzle #360) is on thedownstream side of both the first position and the second position. Thatis, the position in the paper-feed direction of the nozzle #360 isalways on the downstream side of the lower edge position of the printpaper P when detecting the portion of the print paper P located on theupstream side in the paper-feed direction, regardless of theabove-described fluctuation due to the detection error in the lower edgeposition of the print paper P.

If the above-described method for keeping the nozzles positioned on theupstream side of the paper-feed direction from ejecting ink is appliedto this example, then there will be nozzles that do not eject ink eventhough they are required to eject ink because they are in opposition tothe print paper. Therefore, due to such a nozzle operation, a blankportion will appear on the print paper. Further, in order to preventthis blank portion from appearing, there arises a problem that itbecomes necessary to set the above-described predetermined amount to alarger value to secure a larger margin.

Further, when the position, in the paper-feed direction, of the nozzlelocated most upstream in the paper-feed direction (i.e., the nozzle#360) is on the downstream side of both the first position and thesecond position, then the size of the carriage 28 in the paper-feeddirection becomes large, thereby resulting in the apparatus to beincreased in size. More specifically, although the carriage 28 isinherently required to have a size in the paper-feed direction amountingto the length of the nozzle row, it further becomes necessary to provideit with a length for securing the position for attaching the reflectiveoptical sensor.

Compared to these two examples, the example shown in FIG. 11 lessens theproblems described for the above two examples because the position, inthe paper-feed direction, of the nozzle located most upstream in thepaper-feed direction (i.e., the nozzle #360) is located on the upstreamside than the first position and on the downstream side than the secondposition. That is, according to the example shown in FIG. 11, it becomespossible to achieve a printer in which the nozzle located most upstreamin the paper-feed direction is arranged at an ideal position inconsideration of the problems described above.

(1) Other Embodiments

In the foregoing, a liquid ejecting apparatus etc. according to theinvention was described based on an embodiment thereof. However, theforegoing embodiment is for the purpose of elucidating the presentinvention and are not to be interpreted as limiting the presentinvention. The invention can of course be altered and improved withoutdeparting from the gist thereof and includes functional equivalents.

Print paper was described as an example of the medium, but it alsopossible to use film, cloth, and thin metal sheets, and the like as themedium.

In the foregoing embodiment, a printing apparatus was described as anexample of the liquid ejecting apparatus. However, this is not alimitation. For example, technology like that of the embodiment can alsobe adopted for color filter manufacturing devices, dyeing devices, fineprocessing devices, semiconductor manufacturing devices, surfaceprocessing devices, three-dimensional shape forming machines, liquidvaporizing devices, organic EL manufacturing devices (particularlymacromolecular EL manufacturing devices), display manufacturing devices,film formation devices, and DNA chip manufacturing devices. Theabove-described effects can be maintained even when the presenttechnology is adopted in these fields because of the feature that liquidcan be ejected toward a medium.

Further, in the foregoing embodiment, a color inkjet printer wasdescribed as an example of the printing apparatus; however, this is nota limitation. For example, the present invention can also be applied tomonochrome inkjet printers.

Further, in the above embodiment, ink was used as an example of theliquid; however, this is not a limitation. For example, it is alsopossible to eject from the nozzles a liquid (including water) includingmetallic material, organic material (particularly macromolecularmaterial), magnetic material, conductive material, wiring material,film-formation material, processed liquid, and genetic solution.

Further, in the foregoing embodiment, the position, in the paper-feeddirection, of the nozzle located most upstream in the paper-feeddirection, of among the plurality of nozzles, was in the middle of thefirst position and the second position, but this is not a limitation,and it is only necessary that the position is on the upstream side ofthe first position and on the downstream side of the second position.

However, the foregoing embodiment is preferable from the standpointthat, by providing the position, in the paper-feed direction, of thenozzle located most upstream in the paper-feed direction right in themiddle of the first position and the second position, it becomespossible to most effectively lessen the two types of problems describedabove and achieve a printer in which the nozzle located most upstream inthe feeding direction is arranged at an ideal position.

Further, in the foregoing embodiment, the reflective optical sensor wasprovided aligned in the main-scanning direction with the nozzle locatedmost upstream in the paper-feed direction, but this is not a limitation.

In this way, however, the position, in the paper-feed direction, of thenozzle located most upstream in the paper-feed direction becomeslocated, almost certainly, on the upstream side of the first positionand on the downstream side of the second position, and moreover, if theamount of error towards the upstream side from the position of thereflective optical sensor in the paper-feed direction and the amount oferror towards the downstream side therefrom are equal (in the example ofFIG. 11, the amount of error is set to 9·D), then the position will beright in the middle of the first position and the second position. Theforegoing embodiment is therefore more preferable in terms that theabove-described effects can be achieved.

Further, in the foregoing embodiment, the portion of the print paperlocated on the upstream side in the paper-feed direction was detected,and based on this detection result, ink was kept from being ejected fromthe nozzle located most upstream in the paper-feed direction and thenozzles located within a predetermined distance from that nozzle in thepaper-feed direction, of among the plurality of nozzles, but this is nota limitation. For example, some of the nozzles, of among the nozzlelocated most upstream in the paper-feed direction and the nozzleslocated within a predetermined distance from that nozzle in thepaper-feed direction, may eject ink.

However, the above embodiment is more preferable from the standpointthat they allow the amount of ink that is used to be further reduced.

Further, in the foregoing embodiment, the process of feeding the printpaper in the paper-feed direction using the paper feed motor and theprocess of moving the print head so as to print the print paper wererepeated a predetermined number of times after the portion of the printpaper located on the upstream side in the paper-feed direction wasdetected, and then printing to the print paper was ended. This is not alimitation, however.

However, the above embodiment is preferable from the standpoint thatthey allow the print paper to be completely filled with dots.

Further, in the foregoing embodiment, the predetermined number of timeswas a plural number of times, and the predetermined distance in theprocess for printing the print paper was increased in correspondencewith an increase in the aggregate paper feed amount of the print paperafter detection of the portion of the print paper on the upstream sidein the paper-feed direction. However, this is not a limitation, and itis also possible to set the predetermined distance to a distance thatremains constant regardless of the increase in the aggregate paper feedamount, for example.

However, in this case, the above embodiment is preferable from thestandpoint that they allow the number of nozzles that do not eject inkto be increased in correspondence with an increase in the number ofnozzles that are not in opposition to the print paper, consequentlyallowing the amount of ink that is consumed to be further reduced.

Further, in the foregoing embodiment, the value obtained by subtractinga predetermined amount from the aggregate paper feed amount served asthe predetermined distance. However, there is no limitation to this, andfor example, it is also possible to adopt the aggregate paper feedamount as the predetermined distance.

However, the above embodiment is more preferable from the standpointthat they allow a margin to be secured, taking into account thedetection error when the portion of the print paper that is located onthe upstream side in the paper-feed direction is detected.

Further, in the foregoing embodiment, the predetermined amount was madesmaller the higher the detection precision with which the portion of theprint paper located on the upstream side in the paper-feed direction isdetected. However, this is not a limitation, and for example, it is alsopossible to set a value for the predetermined amount that is unrelatedto the detection precision.

However, from the standpoint that the nozzles that are kept fromejecting ink can be more effectively determined by adjusting the amountof the margin in accordance with the degree of detection precision, theabove embodiment is more preferable.

Further, in the foregoing embodiment, the portion of the print paperthat is located on the upstream side in the paper-feed direction wasdetected by determining whether or not the edge of the printing paper onthe upstream side in the paper-feed direction had passed apredetermining position in the paper-feed direction. However, this isnot a limitation.

However, the above embodiment is preferable from the standpoint that theportion of the print paper that is located on the upstream side in thepaper-feed direction can be detected more reliably.

Further, in the foregoing embodiment, the apparatus was provided with aplaten for supporting the print paper, a light-emitting section foremitting light toward the platen, and a light-receiving section forreceiving the light that has been emitted from the light-emittingsection, and by determining whether or not the print paper is in thetraveling direction of the light emitted from the light-emitting sectionbased on the output value of the light-receiving section, it wasdetermined whether or not the edge of the print paper on the upstreamside in the paper-feed direction had passed a predetermined position inthe paper-feed direction. However, there is no limitation to this.

However, the above-mentioned embodiment is more preferable from thestandpoint that whether or not the edge of the print paper that ispositioned on the upstream side in the paper-feed direction has passed apredetermined position in the paper-feed direction can be more easilydetermined.

Further, in the foregoing embodiment, whether or not the print paper wasin the traveling direction of the light was determined based on theoutput value of the light-receiving section for receiving the light thatis emitted from the light-emitting section toward a predeterminedposition in the paper-feed direction on the platen but toward aplurality of different positions in the main-scanning direction on theplaten. However, there is no limitation to this. For example, it is alsopossible to determine whether or not the print paper is in the travelingdirection of the light based on the output value of the light-receivingsection for receiving the light that is emitted from the light-emittingsection toward only a single position that is in a predeterminedposition on the platen in the paper-feed direction.

However, in this case, the above-mentioned embodiment is preferable fromthe standpoint that even if the print paper is skewed, for example, itis possible to reliably detect the portion of the print paper that islocated on the upstream side in the paper-feed direction.

Further, in the foregoing embodiment, the light-emitting section and thelight-receiving section were provided on a carriage that is movable inthe main-scanning direction, and whether or not the print paper is inthe traveling direction of the light was determined based on the outputvalue of the light-receiving section for receiving the light that isemitted from the light-emitting section, while the carriage was moved inthe main-scanning direction, toward a predetermined position in thepaper-feed direction on the platen but toward a plurality of differentpositions in the main-scanning direction on the platen. However, thereis no limitation to this. For example, the positions of thelight-emitting section and the light-receiving section can be fixed, andwhether or not the print paper is in the traveling direction of thelight can be determined based on the output value of the light-receivingsection for receiving the light that is emitted from the light-emittingsection toward a predetermined position in the paper-feed direction onthe platen but a plurality of different positions in the main-scanningdirection on the platen.

However, in this case, the above embodiment is more preferable from thestandpoint that it is not necessary to change the direction in which thelight is emitted for each position when light is emitted from thelight-emitting section toward a plurality of different positions in themain-scanning direction.

Further, in the foregoing embodiment, whether or not the print paper isin the traveling direction of the light was detected based on the outputvalue of the light-receiving section for receiving the light that isemitted from the light-emitting section, while the carriage providedwith the print head was moved in the main-scanning direction, toward apredetermined position in the paper-feed direction but a plurality ofdifferent positions in the main-scanning direction, and also, printingwas performed with respect to the print paper by ejecting ink from thenozzles provided in the print head. However, there is no limitation tothis. For example, it is also possible to adopt a configuration in whichthe carriage and the light emitting and light-receiving sections aremoved in the main-scanning direction individually.

However, in this case, the above embodiment is preferable from thestandpoint that the carriage, the light-emitting section, and thelight-receiving section can share a common moving mechanism.

Further, in the foregoing embodiment, borderless printing was performed.This is not a limitation, however.

In the case of borderless printing, however, since printing is carriedout with respect to the entire surface of the print paper, a situationwhere ink is ejected from nozzles that are not in opposition to theprint paper when a portion of the nozzle surface is not in opposition tothe print paper occurs easily, and therefore, the above-described meansare even more advantageous.

(1) CONFIGURATION OF COMPUTER SYSTEM ETC.

Next, an embodiment of a computer system, which is an example of anembodiment of the present invention, will be described with reference tothe drawings.

FIG. 14 is an explanatory diagram showing the external configuration ofthe computer system. A computer system 1000 is provided with a maincomputer unit 1102, a display device 1104, a printer 1106, an inputdevice 1108, and a reading device 1110. In this embodiment, the maincomputer unit 1102 is accommodated within a mini-tower type housing;however, this is not a limitation. A CRT (cathode ray tube), a plasmadisplay, or a liquid crystal display device, for example, is generallyused as the display device 1104, but this is not a limitation. Theprinter 1106 is the printer described above. In this embodiment, theinput device 1108 is a keyboard 1108A and a mouse 1108B, but it is notlimited to these. In this embodiment, a flexible disk drive device 111Aand a CD-ROM drive device 1110B are used as the reading device 1110, butthe reading device 1110 is not limited to these, and it may also be a MO(magneto optical) disk drive device or a DVD (digital versatile disk),for example.

FIG. 15 is a block diagram showing the configuration of the computersystem shown in FIG. 14. An internal memory 1202 such as a RAM withinthe housing accommodating the main computer unit 1102 and, also, anexternal memory such as a hard disk drive unit 1204 are provided.

In the above description, an example was described in which the computersystem is constituted by connecting the printer 1106 to the maincomputer unit 1102, the display device 1104, the input device 1108, andthe reading device 1110. However, this is not a limitation. For example,the computer system can be made of the main computer unit 1102 and theprinter 1106, or the computer system does not have to be provided withone of the display device 1104, the input device 1108, and the readingdevice 1110.

It is also possible for the printer 1106, for example, to have some ofthe functions or mechanisms of the main computer unit 1102, the displaydevice 1104, the input device 1108, and the reading device 1110. As anexample, the printer 1106 may be configured so as to have an imageprocessing section for carrying out image processing, a display sectionfor carrying out various types of displays, and a recording mediaattachment/detachment section to and from which recording media storingimage data captured by a digital camera or the like are inserted andtaken out.

As an overall system, the computer system that is thus achieved becomessuperior to conventional systems.

According to the foregoing embodiment, it becomes possible to achieve aliquid ejecting apparatus and a computer system in which the nozzlelocated most upstream in the feeding direction is arranged at an idealposition.

(2)

Another embodiment is described next.

It should be noted that the “feeding direction” and the “sub-scanningdirection” described above correspond to the “carrying direction” in thedescription below. Further, the “main-scanning direction” describedabove corresponds to the “scanning direction” in the description below.Further, the print paper P described above corresponds to the paper S inthe description below. Further, the “portion of the print paper locatedon the upstream side in the paper-feed direction” corresponds to the“rear edge” in the description below.

Further, the “reflective optical sensor 29” described above correspondsto the “optical sensor 254” in the description below.

(2) CONFIGURATION OF PRINTING SYSTEM

An embodiment of a printing system (computer system) is described withreference to the drawings. However, the description of the followingembodiment also includes implementations relating to a computer programand a storage medium having recorded thereon the computer program, forexample.

FIG. 16 is an explanatory drawing showing the external structure of aprinting system. A printing system 2100 is provided with a printer 201,a computer 2110, a display device 2120, an input device 2130, and arecord-and-play device 2140. The printer 201 is a printing apparatus forprinting images on a medium such as paper, cloth, or film. The computer2110 is electrically connected to the printer 201, and outputs printdata corresponding to an image to be printed to the printer 201 in orderto print the image with the printer 201. The display device 2120 has adisplay, and displays a user interface such as an application program ora printer driver. The input device 2130 is for example a keyboard 2130Aand a mouse 2130B, and is used to operate an application program oradjust the settings of the printer driver, for example, in accordancewith the user interface that is displayed on the display device 2120. Aflexible disk drive device 2140A and a CD-ROM drive device 2140B areemployed as the record-and-play device 2140.

A printer driver is installed on the computer 2110. The printer driveris a program for achieving the function of displaying the user interfaceon the display device 2120, and in addition it also achieves thefunction of converting image data that have been output from theapplication program into print data. The printer driver is stored on astorage medium (computer-readable storage medium) such as a flexibledisk FD or a CD-ROM. Also, the printer driver can be downloaded onto thecomputer 2110 via the Internet. It should be noted that this program ismade of codes for achieving various functions.

It should be noted that “printing apparatus” in a narrow sense means theprinter 201, but in a broader sense it means the system constituted bythe printer 201 and the computer 2110.

(2) CONFIGURATION OF THE PRINTER

<Regarding the Configuration of the Inkjet Printer>

FIG. 17 is a block diagram of the overall configuration of the printerof this embodiment. Also, FIG. 18 is a schematic diagram of the overallconfiguration of the printer of this embodiment. FIG. 19 is lateralsectional view of the overall configuration of the printer of thisembodiment. The basic structure of the printer according to the presentembodiment is described below.

The printer of this embodiment has a carry unit 220, a carriage unit230, a head unit 240, a detector group 250, and a controller 260. Theprinter 201 that has received print data from the computer 2110, whichis an external device, controls the various units (the carry unit 220,the carriage unit 230, and the head unit 240) using the controller 260.The controller 260 controls the units in accordance with the print datathat are received from the computer 2110 to form an image on a paper.The detector group 250 monitors the conditions within the printer 201,and it outputs the results of this detection to the controller 260. Thecontroller receives the detection results from the sensor, and controlsthe units based on these detection results.

The carry unit 220 is for feeding a medium (for example, paper S) into aprintable position and carrying the paper in a predetermined direction(hereinafter, referred to as the carrying direction) by a predeterminedcarry amount during printing. In other words, the carry unit 220functions as a carrying mechanism (carrying means) for carrying paper.The carry unit 220 has a paper supplying roller 221, a carry motor 222(hereinafter, referred to as PF motor), a carry roller 223, a platen224, and a paper discharge roller 225. However, the carry unit 220 doesnot necessarily have to include all of these structural elements inorder to function as a carrying mechanism. The paper supplying roller221 is a roller for automatically supplying paper that has been insertedinto a paper insert opening into the printer. The paper supplying roller221 has a transverse cross-sectional shape in the shape of the letter D,and the length of the circumference section thereof is set longer thanthe carrying distance to the carry motor 2223, so that using thiscircumference section the paper can be carried up to the carry roller223. The carry motor 222 is a motor for carrying paper in the papercarrying direction, and is constituted by a DC motor. The carry roller223 is a roller for carrying the paper S that has been supplied by thepaper supplying roller 221 up to a printable region, and is driven bythe carry motor 222. The platen 224 supports the paper S duringprinting. That is, the platen 224 functions as a supporting section. Thepaper discharge roller 225 is a roller for discharging the paper S forwhich printing has finished to outside the printer. The paper dischargeroller 225 is rotated in synchronization with the carry roller 223.

The carriage unit 230 is for making the head move (perform scanningmovement) in a predetermined direction (hereinafter, this is referred toas the scanning direction). The carriage unit 230 has a carriage 231 anda carriage motor 232 (also referred to as CR motor). The carriage 231 iscapable of moving back and forth in the scanning direction (andaccordingly, the head moves in the scanning direction). Also, thecarriage 231 detachably retains an ink cartridge for accommodating ink.The carriage motor 232 is a motor for moving the carriage 231 in thescanning direction, and is constituted by a DC motor.

The head unit 240 is for ejecting ink onto paper. The head unit 240 hasa head 241. The head 241 has a plurality of nozzles, which are inkejecting sections, and ejects ink intermittently from each of thenozzles. The head 241 is provided in the carriage 231. Thus, when thecarriage 231 moves in the scanning direction, the head 241 also moves inthe scanning direction. A dot line (raster line) is formed on the paperin the scanning direction as a result of the head 241 intermittentlyejecting ink while moving in the scanning direction.

The detector group 250 includes a linear encoder 251, a rotary encoder252, a paper detection sensor 253, and an optical sensor 254, forexample. The linear encoder 251 is for detecting the position of thecarriage 231 in the scanning direction. The rotary encoder 252 is fordetecting the amount of rotation of the carry roller 223. The paperdetection sensor 253 is for detecting the position of the front edge ofthe paper to be printed. The paper detection sensor 253 is provided in aposition where it can detect the position of the front edge of the paperas the paper is being fed toward the carry roller 223 by the papersupplying roller 221. It should be noted that the paper detection sensor253 is a mechanical sensor that detects the front edge of the paperthrough a mechanical mechanism. More specifically, the paper detectionsensor 253 has a lever that can be rotated in the paper carryingdirection, and this lever is arranged such that it protrudes into thepath over which the paper is carried. In this way, the front edge of thepaper comes into contact with the lever and the lever is rotated, andthus the paper detection sensor 253 detects the position of the frontedge of the paper by detecting movement of the lever. The optical sensor254 is attached to the carriage 231. The optical sensor 254 detectswhether or not the paper is present by its light-receiving sectiondetecting reflected light of the light that has been irradiated onto thepaper from the light-emitting section. The optical sensor 254 detectsthe position of the edge of the paper while being moved by the carriage41. The optical sensor 254 optically detects the edge of the paper, andthus has higher detection accuracy than the mechanical paper detectionsensor 253.

The controller 260 is a control unit (controlling means) for carryingout control of the printer. The controller 260 has an interface section261, a CPU 262, a memory 263, and a unit control circuit 264. Theinterface section 261 exchanges data between the computer 2110, which isan external device, and the printer 201. The CPU 262 is a computerprocessing device for carrying out overall control of the printer. Thememory 263 is for reserving a working region and a region for storingthe programs for the CPU 262, for instance, and has storing means suchas a RAM or an EEPROM. The CPU 262 controls the various units via theunit control circuit 264 in accordance with programs stored in thememory 263.

<Regarding the Printing Operation>

FIG. 20 is a flowchart of the processing during printing. The processesdescribed below are executed by the controller 260 controlling thevarious units in accordance with a program stored in the memory 263.This program has codes for executing the various processes.

The controller 260 receives a print command via the interface section261 from the computer 2110 (S201). This print command is included in theheader of the print data transmitted from the computer 2110. Thecontroller 260 then analyzes the content of the various commandsincluded in the print data that is received and uses the units toperform the following paper supply process, carrying process, and inkejection process, for example.

First, the controller 260 performs the paper supply process (S202). Thepaper supply process is a process for supplying paper to be printed intothe printer and positioning the paper at a print start position (alsoreferred to as the “indexed position”). The controller 260 rotates thepaper supplying roller 221 to feed the paper to be printed up to thecarry roller 223. The controller 260 rotates the carry roller 223 toposition the paper that has been fed from the paper supplying roller 221at the print start position. When the paper has been positioned at theprint start position, at least some of the nozzles of the head 241 arein opposition to the paper.

Next, the controller 260 performs the dot formation process (S203). Thedot formation process is a process for intermittently ejecting ink froma head that moves in the scanning direction so as to form dots on thepaper. The controller 260 drives the carriage motor 232 to move thecarriage 231 in the scanning direction. The controller 260 then causesthe head to eject ink in accordance with the print data during theperiod that the carriage 231 is moving. Dots are formed on the paperwhen ink droplets ejected from the head land on the paper.

Next, the controller 260 performs the carrying process (S204). Thecarrying process is a process for moving the paper relative to the headin the carrying direction. The controller 260 drives the carry motor torotate the carry roller and thereby carry the paper in the carryingdirection. Through this carrying process the head 241 can form dots atpositions that are different from the positions of the dots formed inthe preceding dot formation process.

Next, the controller 260 determines whether or not to discharge thepaper under printing (S205). The paper is not discharged if there arestill data for printing on the paper which is currently being printedon. In this case, the controller 260 alternately repeats the dotformation and carrying processes until there is no longer data forprinting, thereby gradually printing an image made of dots on the paper.When there are no longer data for printing on the paper which iscurrently being printed on, the controller 260 discharges that paper.The controller 260 discharges the printed paper to the outside byrotating the paper discharge roller. It should be noted that whether ornot to discharge the paper can also be determined based on a paperdischarge command included in the print data.

Next, the controller 260 determines whether or not to continue printing(S206). If the next sheet of paper is to be printed, then printing iscontinued and the paper supply process for the next sheet of paper isstarted. If the next sheet of paper is not to be printed, then theprinting operation is ended.

(2) PAPER SUPPLY PROCESSING

FIG. 21 is a flowchart of the paper supply processing. Further, FIG. 22Ato FIG. 22E are explanatory diagrams showing how the paper supplyprocessing is performed as viewed from the upper surface. The variousoperations described below are achieved by the controller controllingthe carry unit 220 based on a program stored in a memory of the printer201. Further, this program is made up of codes for enabling the variousoperations described below.

First, the controller rotates the paper supplying roller (S221). Therotation of the paper supplying roller is started in accordance with apaper-supply command data included in the print data. When the papersupplying roller rotates, the paper is supplied toward the carry roller.The position of the paper S and the structural elements at this timingis as shown in FIG. 22A.

Next, the paper detection sensor 253 detects the front edge of the paper(S222). That is, it is possible to detect that the front edge of thepaper S has reached the position of the paper detection sensor 253 bydetecting the rotation of the lever as the front edge of the paper Scomes into contact with the lever of the paper detection sensor 253. Thepaper detection sensor 253 is provided at a position where it can detectthe paper front edge while the paper supplying roller 221 is supplyingthe paper toward the carry roller 223. Therefore, the paper detectionsensor 253 can detect the front edge of the paper before the front edgeof the paper reaches the carry roller. The position of the paper S andthe structural elements at this timing is as shown in FIG. 22B.

Next, the controller performs paper-skew correction processing (S223).There are cases in which the posture of the paper is skewed with respectto the carrying direction before the paper is carried by the carryroller. Therefore, the controller corrects the skew in the paper bycontrolling the rotation of the paper supplying roller 221.

FIG. 23 is a flowchart of the paper-skew correction processing. Further,FIG. 24A to FIG. 24D are explanatory diagrams of how the paper-skewcorrection processing is performed as viewed from the upper surface. Thevarious operations described below are achieved by the controllercontrolling the carry unit 220 based on a program stored in a memory ofthe printer 201. Further, this program is made up of codes for enablingthe various operations described below.

First, in a state where the rotation of the carry roller 223 is stopped,the controller rotates the paper supplying roller 221 in the forwarddirection (the rotating direction by which the paper is supplied towardthe carry roller) (S223-1; FIG. 24A). When the controller continues thisoperation, the front edge of the paper S comes into contact with thecarry roller 223 (S223-2; FIG. 24B). Next, in a state where the rotationof the carry roller 223 is stopped, the controller further rotates thepaper supplying roller 221 in the forward direction (S223-3). At thistime, since the carry roller 223 is in a stopped state, the paper Scannot move forward in the carrying direction, and thus a slippageoccurs between the paper supplying roller 221 and the paper S, therebycausing the front edge of the paper S to become parallel with the axialdirection of the carry roller 223 (FIG. 24C). Next, the controller makesthe paper supplying roller 221 rotate backwards, to thereby make thefront edge of the paper S move away from the carry roller 223 (S223-4;FIG. 24D).

By performing the above processing, the controller can carry the paperwhile correcting the skew in the paper.

Next, the controller rotates the carry roller 223 (S224). At this time,since the paper supplying roller 221 and the carry roller 223 rotate insynchronization, the paper is carried up to the printable region by thetwo rollers. The position of the paper S and the structural elements atthis timing is as shown in FIG. 22C.

Next, the optical sensor 254 detects the front edge of the paper (S225).The optical sensor is provided at a position where it can detect thefront edge of the paper before the front edge of the paper reaches theprint start position. The controller controls the carry motor such that,when the optical sensor 254 detects the front edge of the paper, thecarry roller 223 rotates by a predetermined rotation amount. Theposition of the paper S and the structural elements at this timing is asshown in FIG. 22D.

If the carry roller 223 is rotated by the predetermined rotation amount,then the front edge of the paper will reach the print start position.That is, since the distance from the position where the optical sensor254 detects the front edge of the paper to the print start position isknown, if the controller rotates the carry roller by the predeterminedrotation amount when the optical sensor 254 detects the front edge ofthe paper, then the front edge of the paper will be positioned at theprint start position. The position of the paper S and the structuralelements at this timing is as shown in FIG. 22E.

(2) CARRYING PROCESS

<Regarding the Carrying Process>

FIG. 25 is an explanatory diagram of showing the structure of the carryunit 220. It should be noted that in this diagram, structural elementsthat have already been described are assigned identical referencenumerals and further description thereof has been omitted.

The carry unit 220 drives the carry motor 222 by a predetermined driveamount in accordance with a carry command from the controller. The carrymotor 222 generates a drive force in the rotation direction thatcorresponds to the drive amount that has been ordered. The carry motor222 then rotates the carry roller 223 using this drive force. The carrymotor 222 also rotates the paper discharge roller 225 using this driveforce. That is, when the carry motor 222 generates a predetermined driveamount, the carry roller 223 and the paper discharge roller 225 rotateby a predetermined rotation amount. When the carry roller 223 and thepaper discharge roller 225 are rotated by the predetermined rotationamount, the paper is carried by a predetermined carry amount. Becausethe carry roller 223 and the paper discharge roller 225 rotate insynchronization, the paper can be carried by the carry unit 220 as longas the paper is in contact with at least one of the carry roller 223 andthe paper discharge roller 225.

The carry amount, by which the paper is carried, is determined accordingto the rotation amount of the carry roller 223. Consequently, if therotation amount of the carry roller 223 can be detected, then it is alsopossible to detect the carry amount of the paper. Accordingly, therotary encoder 252 is provided in order to detect the rotation amount ofthe carry roller 223.

<Regarding the Structure of the Rotary Encoder>

FIG. 26 is an explanatory diagram of the configuration of the rotaryencoder. It should be noted that in this diagram, structural elementsthat have already been described are assigned identical referencenumerals and further description thereof has been omitted.

The rotary encoder 252 has a scale 2521 and a detecting section 2522.

The scale 2521 has numerous slits provided at predetermined intervals.The scale 2521 is provided in the carry roller 223. That is, the scale2521 rotates together with the carry roller 223 when the carry roller223 is rotated. For example, when the carry roller 223 is rotated suchthat the paper S is carried by 1/1440 inch, the scale 2521 is rotated byone slit with respect to the detecting section 2522.

The detecting section 2522 is provided in opposition to the scale 2521,and is fastened on the printer body side. The detecting section 2522 hasa light-emitting diode 2522A, a collimating lens 2522B, and a detectionprocessing section 2522C. The detection processing section 2522C isprovided with a plurality of (for instance, four) photodiodes 2522D, asignal processing circuit 2522E, and two comparators 2522Fa and 2522Fb.

The light-emitting diode 2522A emits light when a voltage Vcc is appliedto it via resistors on both sides, and this light is incident on thecollimating lens. The collimating lens 2522B turns the light that isemitted from the light-emitting diode 2522A into parallel light, andirradiates the parallel light on the scale 2521. The parallel light thathas passed through the slits provided in the scale then passes throughstationary slits (not shown) and is incident on the photodiodes 2522D.The photodiodes 2522D convert the incident light into electric signals.The electric signals that are output from the photodiodes are comparedin the comparators 2522Fa and 2522Fb, and the results of thesecomparisons are output as pulses. Then, the pulse ENC-A and the pulseENC-B that are output from the comparators 2522Fa and 2522Fb become theoutput of the rotary encoder 252.

<Regarding the Signals of the Rotary Encoder>

FIG. 27A is a timing chart of the waveforms of the output signals whenthe carry motor 222 is rotating forward. FIG. 27B is a timing chart ofthe waveforms of the output signals when the carry motor 222 is rotatingin reverse.

As shown in the figure, the phases of the pulse ENC-A and the pulseENC-B are misaligned by 90 degrees both when the carry motor 12 isrotating forward and when it is rotating in reverse. When the carrymotor 222 is rotating forward, that is, when the paper S is carried inthe carrying direction, then the phase of the pulse ENC-A leads thephase of the pulse ENC-B by 90 degrees. On the other hand, when thecarry motor 222 is rotating in reverse, that is, when the paper S iscarried in the direction opposite from the carrying direction, then thephase of the pulse ENC-A trails the phase of the pulse ENC-B by 90degrees. A single period T of the pulses is the same as the time duringwhich the carry roller 223 is rotated by an interval of the slits of thescale 2521 (for example, by 1/1440 inch (1 inch=2.54 cm)).

By counting the number of pulse signals with the controller, therotation amount of the carry roller 223 can be detected, and thus thecarry amount of the paper can be detected. Also, by detecting a singleperiod T of the pulses with the controller, the rotation velocity of thecarry roller 223 can be detected, and thus the carry velocity of thepaper can be detected.

<Regarding the Flow of Carrying>

FIG. 28 is a flowchart of the carrying process. The various operationsthat are described below are achieved by the controller controlling thecarry unit 220 based on a program stored in the memory in the printer201. Also, this program is made of codes for performing the variousoperations described below.

First, the controller sets a target carry amount (S241). The targetcarry amount is a value determining the drive amount of the carry unit220 in order for the carry unit 220 to carry the paper S by a carryamount that has been defined as a target. The target carry amount isdetermined based on carry command data (information about the targetcarry amount) included in the print data that are received from thecomputer side. The target carry amount is set by setting the value ofthe counter with the controller. In the following description, thetarget carry amount is defined as X, and thus the controller sets thevalue of the counter to X.

Next, the controller drives the carry motor 222 (S242). When the carrymotor 222 generates a predetermined drive amount, the carry roller 223is rotated by a predetermined rotation amount. Then, the slits 521provided in the carry roller 223 are also rotated when the carry roller223 is rotated by the predetermined rotation amount.

Next, the controller detects the edge of the pulse signal of the rotaryencoder (S243). That is, the controller detects the rising edge or thefalling edge of the pulse ENC-A or the pulse ENC-B. For example, if thecontroller detects one edge, then this means that the carry roller 223has carried the paper S by a carry amount of 1/1440 inch.

When the controller has detected an edge of the pulse signal of therotary encoder, the controller subtracts this from the value of thecounter (S244). That is, if the value of the counter is X, then thecontroller sets the value of the counter to X-1 when it has detected oneedge of the pulse signal.

Next, the controller repeats the operations of S242 to S244 until thevalue of the counter becomes zero (S245). That is, the controller drivesthe carry motor 222 until the same number of pulses as the valueinitially set in the counter have been detected. In this fashion, thecarry unit 220 carries the paper S in the carrying direction by a carryamount that corresponds to the value initially set in the counter.

For example, for the carry unit 220 to carry the paper S by 90/1440inch, the controller sets the value of the counter to 90, therebysetting the target carry amount. The controller then decrements thevalue of the counter each time that it detects a rising edge or afalling edge of the pulse signal of the rotary encoder. Then, when thevalue of the counter has reached zero, the controller ends the carryingoperation. This is because the detection of 90 pulse signals means thatthe carry roller 223 has carried the paper S by 90/1440 inch.Consequently, if the controller sets the value of the counter to 90 asthe settings for the target carry amount, then the result is that thecarry unit 220 carries the paper S by 90/1440 inch.

It should be noted that in the foregoing description, the controllerdetects the rising edge or the falling edge of the pulse ENC-A or thepulse ENC-B, but it is also possible for it to detect both edges of thepulse ENC-A and the pulse ENC-B. The cycles of the pulse ENC-A and thepulse ENC-B are equal to the slit intervals of the scales 2521 and thephases of the pulse ENC-A and the pulse ENC-B are misaligned by 90degrees, and therefore, detection by the controller of either the risingedge or the falling edge of the pulses means that the carry roller 223has carried the print paper by 1/5760 inch. In the present case, if thecontroller sets the value of the counter to 90, then the carry unit 220carries the paper S by 90/5760 inch.

The foregoing description is for a single carrying operation. If theprinter is to intermittently perform the carrying operation for aplurality of times, then the controller sets the target carry amount(sets the value of the counter) each time the carrying operation isfinished, and the carry unit 220 carries the paper S in accordance withthe target carry amount that has been set.

Incidentally, the rotary encoder 252 directly detects the rotationamount of the carry roller 223, and strictly speaking, does not detectthe carry amount of the paper S. That is, if slippage occurs between thecarry roller 223 and the paper S, then the rotation amount of the carryroller 223 and the carry amount of the paper S will not match, and thusthe rotary encoder 252 cannot accurately detect the carry amount of thepaper S, resulting in a carry error (detection error). When slippageoccurs between the carry roller 223 and the paper S in this manner, itis necessary for the controller to rotate the carry roller 223 by alarger carry amount than the target carry amount in order for the carryunit 220 to carry the paper S by the target carry amount. Accordingly,the controller is capable of correcting the target carry amount andsetting the counter to a value that corresponds to the corrected targetcarry amount in order to carry the paper S by the most suitable carryamount.

(2) ARRANGEMENT OF THE NOZZLES

FIG. 29 is an explanatory diagram showing the arrangement of nozzles inthe lower surface of the head 241. A black ink nozzle group K, a cyanink nozzle group C, a magenta ink nozzle group M, and a yellow inknozzle group Y are formed in the lower surface of the head 241. Eachnozzle group is provided with a plurality of nozzles (in thisembodiment, 180 nozzles), which are ejection openings for ejecting inkof the respective colors.

The plurality of nozzles in each nozzle group are arranged in a row at aconstant spacing (nozzle pitch: k·D) in the carrying direction. Here, Dis the minimum dot pitch in the carrying direction (that is, theinterval between dots, which are formed on the paper S, at the maximumresolution). Furthermore, k is an integer that is 1 or greater. Forexample, if the nozzle pitch is 180 dpi ( 1/180 inch), and the dot pitchin the carrying direction is 720 dpi ( 1/720), then k=4.

The nozzles in each nozzle group are assigned a number (#1 to #180) thatbecomes smaller the more downstream the nozzle is positioned. That is,the nozzle #1 is positioned more downstream in the carrying directionthan the nozzle #180. Each nozzle is provided with a piezo element (notshown) as a drive element for driving the nozzle and causing it to ejectan ink droplet. Also, the optical sensor 254 is arranged at a positionon the upstream side of the most upstream nozzle #180 (i.e., the nozzlemost upstream in the carrying direction) as regards its position in thecarrying direction. The attachment position of the optical sensor 254 isdescribed in detail below.

(2) DETAILED DESCRIPTION OF THE OPTICAL SENSOR

<Regarding the Configuration of the Optical Sensor>

FIG. 30 is an explanatory diagram of a configuration of the opticalsensor 254. The optical sensor 254 is a reflective-type optical sensorhaving a light-emitting section 541 and a light-receiving section 542.The light-emitting section 541 includes, for example, a light emittingdiode, and emits light onto the paper. The light-receiving section 542includes, for example, a phototransistor, and detects the reflectedlight of among the light emitted onto the paper from the light-emittingsection. If the paper S does not exist in the region onto which thelight-emitting section 541 emits light, then the amount of reflectedlight received by the light-receiving section 542 becomes small. If thepaper S exists in the region onto which the light-emitting section 541emits light, then the amount of reflected light received by thelight-receiving section 542 becomes large. The light-receiving section542 outputs signals in accordance with the amount of reflected lightthat it receives.

<Regarding the Output Signal of the Optical Sensor>

FIG. 31 is an explanatory diagram of output signals of the opticalsensor 254. The graph shown on the upper side of the figure is a graphshowing a relationship between the position of the edge of the paper Sand the output signal of the optical sensor 254. The diagrams on thelower side of the figure are diagrams showing relationships between theposition of the edge of the paper S and the detection spot of theoptical sensor. In the figure, the circle indicates the detection spot(detection region) of the optical sensor, and more specifically, itindicates the region onto which the light from the light-emittingsection of the optical sensor 254 is emitted. The region within thecircle that is filled in with black indicates that the light from thelight-emitting section of the optical sensor 254 is being emitted on thepaper S.

In state A (i.e., in a state where the edge of the paper S is outsidethe detection spot of the optical sensor and the paper S is not in thedetection spot), the light from the light-emitting section of theoptical sensor 254 is not emitted onto the paper S. Therefore, thelight-receiving section of the optical sensor 254 cannot detect thereflected light. The output voltage of the optical sensor at this timebecomes Va. In state B (i.e., in a state where the edge of the paper Sis inside the detection spot of the optical sensor and the paper S is ina portion of the detection spot), a portion of the light from thelight-emitting section of the optical sensor 254 is emitted on the paperS. The output voltage of the optical sensor 254 at this time becomes Vb.In state C (i.e., in a state where the edge of the paper S is inside thedetection spot of the optical sensor and the paper S is in almost theentire detection spot), almost all of the light from the light-emittingsection of the optical sensor 254 is emitted on the paper S. The outputvoltage of the optical sensor 254 at this time becomes Vc. In state D(i.e., in a state where the edge of the paper S is outside the detectionspot of the optical sensor and the paper S is in the entire detectionspot), all of the light from the light-emitting section of the opticalsensor 254 is emitted on the paper S. The output voltage of the opticalsensor at this time becomes Vd. As apparent from the figure, the largerthe region occupied by the paper S in the detection spot of the opticalsensor 254, the larger the output signal of the optical sensor 254becomes.

When an output value Vt is set as a threshold, the controller determinesthe state A and the state B as a “no paper state”. When the controllermakes a determination of a “no paper state”, then the printer performsthe various operations assuming that there is no paper at the positionof the optical sensor. On the other hand, when the output value Vt isset as a threshold, the controller determines the state C and the stateD as a “paper existing state”. When the controller makes a determinationof a “paper existing state”, then the printer performs the variousoperations assuming that there is paper at the position of the opticalsensor.

The output value Vt can be set freely within a range from Va to Vd;here, it is equal to the output value of the optical sensor 254 for whenthe paper S occupies half of the detection spot.

<Regarding the Attachment Position of Optical Sensor>

FIG. 32 is an explanatory diagram of an attachment position of theoptical sensor 254. Structural elements that have already been describedare assigned identical reference numerals, and further description ofthose structural elements has been omitted. In the figure, the carriage231 is movable in a direction perpendicular to the paper face (i.e., inthe scanning direction). Further, the optical sensor 254 is attached tothe carriage 231 and is movable in the scanning direction. Further, inthe figure, the “print region” is a region that is in opposition to thenozzle #1 to nozzle #180 of the head 241, and is a region on which theink ejected from the nozzles lands. Further, in the figure, the“detection spot” is the region onto which the light from thelight-emitting section of the optical sensor 254 is emitted, and is thesame region as the region indicated by the circle in FIG. 31 describedabove.

The optical sensor 254 is arranged on the upstream side, in the carryingdirection, of the most upstream nozzle #180. That is, the optical sensor254 is more on the upstream side than the position A in the figure.Therefore, the detection spot of the optical sensor 254 is positioned onthe upstream side, in the carrying direction, of the print region.Therefore, when the paper S is carried from the carry roller 223 towardthe print region, the front edge (upper edge) of the paper S reaches thedetection spot of the optical sensor 254 before reaching the printregion. In other words, the optical sensor 254 is able to detect thefront edge of the paper S before the front edge of the paper S becomesprintable.

Similarly, when the rear edge of the paper S moves away from the carryroller 223 and the paper S is carried by the paper discharge roller 225,the rear edge (lower edge) of the paper S reaches the detection spot ofthe optical sensor 254 before reaching the print region. In other words,the optical sensor 254 is able to detect the rear edge of the paper Sbefore the rear edge of the paper S becomes printable.

Further, during printing, the paper S is carried intermittently by apredetermined carry amount. The optical sensor 254 is positioned on theupstream side with respect to the nozzle #180 by more than a carryamount for a single carry. That is, the optical sensor 254 is positionedon the upstream side, in the carrying direction, away from the nozzle#180 by more than a carry amount for a single carry. In other words, theoptical sensor 254 is more on the upstream side than the position B inthe figure. For example, according to a certain print mode, the carryamount for a single carry is 50/1440 inch, and so the optical sensor 254is provided away from the nozzle #180 by 50/1440 inch or more.Therefore, when printing on the rear edge of the paper S (describedlater), a dot formation process (S203) is performed at least once duringa period from when the optical sensor 254 detects the rear edge of thepaper S up to when the rear edge reaches the print region.

Further, the optical sensor 254 is on the upstream side, in the carryingdirection, of the nozzle #180, but is on the downstream side, in thecarrying direction, of the carry roller 223. That is, the optical sensor254 is more on the downstream side than the position C in the figure.The reason to this is described below. After the optical sensor 254 hasdetected the front edge of the paper, the controller controls the carryamount of the paper based on the result of the detection of the opticalsensor 254 and positions the paper such that the front edge of the paperis at the print start position. (the indexed position) On the otherhand, as described above, before the carry roller 223 carries the paper,the paper-skew correction processing is performed (refer to FIG. 23 andFIG. 24). In the paper-skew correction processing, the controllerrotates the paper supplying roller 221 in a state where the carry roller223 is stopped, and the skew in the paper is corrected by causing aslippage between the paper supplying roller 221 and the paper.Therefore, if the optical sensor 254 is provided on the upstream side ofthe carry roller 223 in the carrying direction, then it is not possibleto correctly position the front edge of the paper at the print startposition due to the slippage between the paper supplying roller 221 andthe paper when performing the paper-skew correction. That is, it ispreferable for the optical sensor 254 to be able to detect the frontedge of the paper after the paper-skew correction processing isfinished. Therefore, in the present embodiment, the optical sensor 254is arranged on the downstream side, in the carrying direction, of thecarry roller 223.

Further, not only is the optical sensor 254 arranged on the downstreamside of the carry roller 223, it is arranged such that its detectionspot is on the platen. In other words, the optical sensor 254 is on thedownstream side of the position D in the figure. The reason to this isdescribed below. The amount of light emitted by the light-emittingsection of the optical sensor 254 of the present embodiment changes dueto deterioration, even when the voltage applied to the light-emittingsection is the same. When the amount of light emitted by thelight-emitting section changes, the amount of light received by thelight-receiving section changes, and thus, the position of the edge ofthe paper that is detected by the optical sensor 254 also changes.Therefore, as for the optical sensor 254 of the present embodiment, thevoltage applied to the light-emitting section is controlled based on theoutput signal of the light-receiving section in a state where there isno paper. In this case, the light-emitting section of the optical sensoremits light onto the platen 224, and control is performed such that theoutput signal of the light-receiving section at this time becomesconstant. In other words, as for the optical sensor 254 of the presentembodiment, calibration is performed based on the output signal in astate in which the platen is not supporting the paper. If the detectionspot of the optical sensor 254 includes the carry roller 223, then, thelight-receiving section will receive a large amount of reflected lightbecause the carry roller 223 is made of metal; therefore, even in astate where there is no paper, the output signal will be the same asthat for a state where there is paper, and thus, it will not be possibleto detect the degree of deterioration of the optical sensor 254.Therefore, in the present embodiment, the optical sensor 254 is arrangedsuch that the detection spot is on the platen.

Further, not only is the optical sensor arranged such that its detectionspot is on the platen, but it is arranged such that the detection spotof the optical sensor is positioned at a position where the posture ofthe paper is stable. In other words, the optical sensor 254 is arrangedmore on the downstream side than the position E in the figure. Theposition where the posture of the paper is stable (position E) isdescribed below.

FIG. 33A to FIG. 33D are explanatory diagrams showing how the paper S iscarried from the carry roller 223 toward the print region. Structuralelements that have already been described are assigned identicalreference numerals, and further description of those structural elementshas been omitted. If the paper is being carried by both the carry roller223 and the paper discharge roller 225 as shown in FIG. 33D, then thepaper will not lift up from the platen in the print region positionedbetween the carry roller 223 and the paper discharge roller 225.However, the paper is carried only by the carry roller 223 during thepaper-supplying process and before the front edge of the paper reachesthe paper discharge roller 225, and therefore, the paper tends to liftup from the platen and the front edge of the paper tends to come closeto the head 241. Therefore, in the present embodiment, the paper issupplied in a slanted manner with respect to the platen 224, as shown inFIG. 33A. Then, by carrying the paper such that it abuts against theplaten as shown in FIG. 33B and FIG. 33C, the front edge of the paper isprevented from lifting up from the platen 224, even before the frontedge of the paper reaches the paper discharge roller 225. It should benoted that the position E in the figure is the position at which thefront edge of the paper first comes into contact with the platen 224.

Since the paper is supplied in a slanted manner with respect to theplaten 224 as described above, the paper S is away from the platen 224on the upstream side of the position E in the figure. If the detectionspot of the optical sensor 254 is arranged at a position where the paperS is away from the platen 224, then there is a possibility that theoptical sensor 254 cannot correctly detect the position of the frontedge of the paper. Therefore, in the present embodiment, the opticalsensor 254 is arranged more on the downstream side than the position E.

By the way, the optical sensor 254 detects whether or not the paper ispresent using regular reflection (FIG. 30). Therefore, the position ofthe center of the detection spot (the center of detection) of theoptical sensor 254 matches the position right in the middle, in thecarrying direction, of the light-emitting section 541 and thelight-receiving section 541 of the optical sensor 254. However, if theoptical sensor 254 uses diffuse reflection for detecting whether or notthe paper is present, then the position of the center of the detectionspot may not necessarily be right in the middle of the light-emittingsection 541 and the light-receiving section 541 of the optical sensor254.

The detection spot of the optical sensor 254 does not converge on onepoint, but occupies a predetermined region. In other words, thedetection spot of the optical sensor 254 has a predetermined width inthe carrying direction. Therefore, it is preferable for the opticalsensor 254 to be arranged taking into consideration the width of thedetection spot. In other words, it is preferable to arrange the opticalsensor 254 such that the entire detection spot of the optical sensor 254is in an appropriate position.

For example, it is preferable for the position, on the most downstreamside in the carrying direction, of the detection spot of the opticalsensor 254 to be positioned on the upstream side, in the carryingdirection, of the nozzle #180 (i.e., on the upstream side in thecarrying direction of the position A). Further, it is preferable for theposition, on the most downstream side in the carrying direction, of thedetection spot of the optical sensor 254 to be positioned on theupstream side, in the carrying direction, away from the nozzle #180 bymore than a carry amount for a single carry (i.e., on the upstream sidein the carrying direction of the position B). Furthermore, it ispreferable for the position, on the most upstream side in the carryingdirection, of the detection spot of the optical sensor 254 to bepositioned on the downstream side of the carry roller 223 (i.e., on thedownstream side in the carrying direction of the position C).Furthermore, it is preferable for the position, on the most upstreamside in the carrying direction, of the detection spot of the opticalsensor 254 to be on the platen 224 (i.e., on the downstream side in thecarrying direction of the position D). Furthermore, it is preferable forthe position, on the most upstream side in the carrying direction, ofthe detection spot of the optical sensor 254 to be positioned on thedownstream side of the position at which the front edge of the paperfirst comes into contact with the platen 224 (i.e., on the downstreamside in the carrying direction of the position E).

Further, the detection spot of the optical sensor 254 is not the samefor all printers, but there are individual differences among theprinters. For example, there is about a±0.3 mm variation in the width,in the carrying direction, of the detection spot of the optical sensor254. Therefore, it is preferable to arrange the optical sensor 254taking into consideration the variation in the width of the detectionspot.

For example, it is preferable that the position, on the most downstreamside in the carrying direction, of the detection spot of an averageoptical sensor 254 is positioned 0.3 mm further upstream, in thecarrying direction, from the position A. Further, it is preferable thatthe position, on the most downstream side in the carrying direction, ofthe detection spot of an average optical sensor 254 is positioned 0.3 mmfurther upstream, in the carrying direction, from the position B.Further, it is preferable that the position, on the most upstream sidein the carrying direction, of the detection spot of an average opticalsensor 254 is positioned 0.3 mm further downstream, in the carryingdirection, from the position C. Furthermore, it is preferable that theposition, on the most upstream side in the carrying direction, of thedetection spot of an average optical sensor 254 is positioned 0.3 mmfurther downstream, in the carrying direction, from the position D.Furthermore, it is preferable that the position, on the most upstreamside in the carrying direction, of the detection spot of an averageoptical sensor 254 is positioned 0.3 mm further downstream, in thecarrying direction, from the position E.

It should be noted that when attaching the optical sensor 254 to thecarriage 231, a variation in the attachment position occurs due totolerance. Therefore, it is preferable to design the optical sensor 254such that, if attached within the range of tolerance, the wholedetection spot of the optical sensor 254 is in an appropriate position.It should be noted that the variation in the attachment position due totolerance is, for example, 0.5 mm.

(2) BORDERLESS PRINTING

FIG. 34 is an explanatory diagram of borderless printing. “Borderlessprinting” is printing carried out over the entire surface of the paper.In the figure, the rectangle on the inner side which is drawn with thesolid line shows the size of the paper. In the figure, the rectangle onthe outside which is drawn with the solid line shows the size of theprint data. In borderless printing, printing is carried out over theentire surface of the paper by ejecting ink onto a region that is largerthan the paper. Therefore, the size of the print data is larger than thesize of the paper. For this reason, the printer ejects ink also to theoutside of the range of the paper.

However, if the amount of ink that does not land on the paper is large,then the amount of consumption of ink will become large, and this is notpreferable. Therefore, waste of ink is prevented by masking the printdata to make the region to which ink is ejected small. The rectangledrawn with the dashed line in the figure shows the region onto which theprinter ejects ink based on masked print data. The region onto which inkis ejected is determined by the controller based on the output of theoptical sensor.

<Regarding the Lateral Edge Processing>

FIG. 35A is an explanatory diagram of detection of the lateral edge ofthe paper. The hatched section in the figure shows the region in whichdots are formed on the paper (the region that is printed). While thecarriage 231 is moving in the scanning direction, the head 241intermittently ejects ink to form dots in the hatched section of thefigure and print a band-like strip of image on the paper. Since thecarriage moves back and forth in the scanning direction during the dotformation process, the optical sensor 254 also moves back and forth inthe scanning direction, and the optical sensor 254 can detect theposition of both lateral edges of the paper.

FIG. 35B is an explanatory diagram of the lateral edge processing inborderless printing. The band-like rectangle in the figure shows printdata for a single pass. It should be noted that a single pass means anoperation in which the carriage 231 moves once in the scanningdirection. More specifically, the band-like rectangle in the figureindicates data that is necessary for the nozzle #1 to nozzle #180 toeject ink during a single pass. The print data in the hatched section inthe figure indicates print data that was used to eject ink from the head241. On the other hand, the print data without the hatching in thefigure indicates print data that was replaced by NULL data as a resultof being masked, thereby resulting in the ink not being ejected from thehead 241.

During the dot formation process, the lateral edge of the paper isdetected by the optical sensor 254. Normally, it should be possible tocomplete borderless printing just by using only the print datacorresponding to the inside of the detected paper to eject ink, becausethis will result in the entire surface of the paper being printed.However, if the paper is carried skewed, then a blank section will beformed at the lateral edges of the paper, and thus it will not bepossible to perform fine borderless printing. Therefore, the print datais masked, leaving a predetermined margin to allow for error due to thepaper being carried skewed, and the region in which ink is ejected isset slightly wider than the lateral edges of the paper.

In the present embodiment, as described above, the optical sensor 254 isarranged on the upstream side of the nozzle #180. Therefore, the regionwhere the optical sensor 254 detects whether or not the paper is presentis away from the region in which the dots are formed on the paper. Ifink is ejected in the detection spot of the optical sensor 254, then theprecision of detection of the optical sensor 254 will drop. On the otherhand, since in the present embodiment ink is not ejected in thedetection spot of the optical sensor 254, it is possible for the opticalsensor 254 to detect the lateral edges of the paper with high precision.As a result, it is possible to perform high-quality borderless printing,or suppress waste of ink as much as possible.

<Regarding the Rear Edge Processing>

FIG. 36A to FIG. 36C are explanatory diagrams of the rear edgeprocessing of the present embodiment. Structural elements that havealready been described are assigned identical reference numerals, andfurther description of those structural elements has been omitted. Inthe figure, the hatched section of the head 241 indicates that thenozzles within that region are to eject ink.

As shown in FIG. 36A, in normal dot formation process, if the opticalsensor 254 detects a “paper existing state”, then ink is ejected fromall of the nozzles because all of the nozzles in the head 241 are inopposition to the paper. Then, after the dot formation process, thecarrying process is performed at a predetermined carry amount.

As shown in FIG. 36B, as a result of the carrying process, the opticalsensor 254 detects a “no paper state” when the rear edge of the paperpasses the optical sensor 254. On the other hand, in the presentembodiment, the optical sensor 254 is on the upstream side, in thecarrying direction, away from the nozzle #180 by more than a carryamount for a single carry, as described above. Therefore, even when theoptical sensor 254 detects a “no paper state”, all of the nozzles ejectink because all of the nozzles provided in the head 241 are inopposition to the paper. Then, during the dot formation process in thestate shown in the figure, the controller determines the nozzles forejecting ink in the next pass in accordance with the timing at which theoptical sensor 254 detects a “no paper state”. That is, the controllerdetermines the nozzles to be used in the next pass based on the resultof detection of the optical sensor 254, such that ink is not ejected inthe next pass from the nozzles on the upstream side of the rear edge ofthe paper. Then, after the dot formation process in the state shown inthe figure, the carrying process is performed to further carry the paperby a predetermined carry amount in order to print on the rear edge ofthe paper.

Then, as shown in FIG. 36C, ink is not ejected from the nozzles on theupstream side of the rear edge of the paper, and ink is ejected from thenozzles on the downstream side of the rear edge of the paper to formdots on the rear edge of the paper.

In the present embodiment, according to the rear edge processingdescribed above, it is possible to print on the rear edge of the paperwhile suppressing waste of ink as much as possible.

FIG. 37A and FIG. 37B are explanatory diagrams of the rear edgeprocessing of a reference example. The attachment position of theoptical sensor 254 is different compared to the present embodiment. Inthe reference example, the optical sensor 254 is arranged on thedownstream side, in the carrying direction, of the nozzle #180.

In the reference example, even when the rear edge of the paper passesthe optical sensor 254, there is no time for the controller to determinethe nozzles to be used based on the detection results of the opticalsensor. Therefore, as shown in FIG. 37B, wasteful ink that does not landon the rear edge of the paper is ejected. Even if the controllerdetermines the nozzles to be used based on the determination results ofthe optical sensor, since it is not possible to perform printing whilethe controller is performing calculation, it will take much time forprinting.

On the other hand, according to the present embodiment, the opticalsensor 254 is arranged on the upstream side of the nozzle #180, asdescribed above. Therefore, the rear edge of the paper passes thedetection spot of the optical sensor 254 before it passes the nozzle#180, and thus, it is possible to suppress waste of ink as much aspossible. Further, according to the present embodiment, the opticalsensor 254 is on the upstream side, in the carrying direction, away fromthe nozzle #180 by more than a carry amount for a single carry, asdescribed above. Therefore, at least the dot formation process isperformed once during the period from when the rear edge of the paperhas passed the detection spot of the optical sensor 254 up to when therear edge reaches the print region (the region on the downstream side,in the carrying direction, of the nozzle #180). As a result, in thepresent embodiment, it is possible for the controller to performcalculation for the nozzles to be used during this dot formationprocess, and therefore, it becomes possible to print on the rear edge ofthe paper at high speed while suppressing waste of ink as much aspossible.

(2) Other Embodiments

The foregoing embodiment described primarily a printer. However, it goeswithout saying that the foregoing description also includes thedisclosure of printing apparatuses, recording apparatuses, liquidejection apparatuses, printing methods, recording methods, liquidejection methods, printing systems, recording systems, computer systems,programs, storage media storing programs, display screens, screendisplay methods, and methods for producing printed material, forexample.

Also, a printer, for example, serving as an embodiment was describedabove. However, the foregoing embodiment is for the purpose ofelucidating the present invention and is not to be construed as limitingthe present invention. The invention can of course be altered andimproved without departing from the gist thereof and includesequivalents. In particular, the implementations mentioned below are alsoincluded in the invention.

<Regarding the Optical Sensor>

According to the foregoing embodiment, the sensor provided on thecarriage was a reflective-type optical sensor. The sensor, however, isnot limited to that of the foregoing embodiment because it is onlynecessary for it to detect the edge of the paper.

For example, the sensor provided on the carriage may be atransmission-type sensor in which the edge of the paper is detected bydetecting whether or not the light is blocked. Further, it may be amechanical sensor.

<Regarding the Printer>

A printer was described in the foregoing embodiment, but this is not alimitation. For example, technology like that of the embodiment can alsobe adopted for various recording apparatuses that use the inkjettechnology such as color filter manufacturing devices, dyeing devices,fine processing devices, semiconductor manufacturing devices, surfaceprocessing devices, three-dimensional shape forming machines, liquidvaporizing devices, organic EL manufacturing devices (particularlymacromolecular EL manufacturing devices), display manufacturing devices,film formation devices, and DNA chip manufacturing devices. Further,methods for such devices and manufacturing methods thereof are withinthe scope of application. When the present technology is adopted inthese fields, a reduction in material, process steps, and costs can beachieved compared to conventional art, because of the feature thatliquid can be directly ejected (directly rendered) on an object.

<Regarding the Ink>

Since the foregoing embodiment was an embodiment of a printer, a dye inkor a pigment ink was ejected from the nozzles. However, the liquid thatis ejected from the nozzles is not limited to such inks. For example, itis also possible to eject from the nozzles a liquid (including water)including metallic material, organic material (particularlymacromolecular material), magnetic material, conductive material, wiringmaterial, film-formation material, electronic ink, processed liquid, andgenetic solutions. A reduction in material, process steps, and costs canbe achieved if such liquids are directly ejected toward a target object.

<Regarding the Nozzles>

In the foregoing embodiment, ink was ejected using piezoelectricelements. However, the method for ejecting liquid is not limited tothis. Other methods may also be employed, such as a method forgenerating bubbles in the nozzles through heat.

With the printing apparatus described above, it is possible to arrangethe sensor for detecting the edge of the paper at the most suitableposition, and to suppress waste of ink that is ejected from the nozzles.

INDUSTRIAL APPLICABILITY

With the liquid ejecting apparatus (printing apparatus) of the foregoingembodiments, it is possible to arrange the sensor for detecting the edgeof the paper at the most suitable position, and to suppress waste of inkthat is ejected from the nozzles.

1. A liquid ejecting apparatus comprising: a movable head that isprovided with a plurality of nozzles for ejecting a liquid; a carry unitfor carrying a medium in a predetermined carrying direction; and asensor for detecting an edge of said medium; wherein said liquidejecting apparatus controls ejection of said liquid from said pluralityof nozzles in accordance with a result of the detection of said sensor;and wherein a position, in the carrying direction, of said sensor is atthe same position of or on an upstream side of a nozzle located mostupstream in said carrying direction, of among said plurality of nozzles.2. A liquid ejecting apparatus comprising: a movable head that isprovided with a plurality of nozzles for ejecting a liquid; a carry unitfor carrying a medium in a predetermined carrying direction; and asensor for detecting an edge of said medium; wherein said liquidejecting apparatus controls ejection of said liquid from said pluralityof nozzles in accordance with a result of the detection of said sensor;wherein, due to a detection error in said sensor that occurs when saidsensor detects the edge of said medium, a position of the edge of saidmedium when said edge is detected fluctuates within a range from a firstposition to a second position; and wherein a position, in said carryingdirection, of a nozzle located most upstream in said carrying direction,of among said plurality of nozzles, is between said first position andsaid second position.
 3. A liquid ejecting apparatus according to claim2, wherein the position, in said carrying direction, of said nozzlelocated most upstream in said carrying direction is in the middle ofsaid first position and said second position.
 4. A liquid ejectingapparatus according to claim 2, wherein said sensor detects the edge ofsaid medium; and wherein, based on a result of this detection, theliquid is kept from being ejected from said nozzle located most upstreamin said carrying direction and nozzles located within a predetermineddistance from that nozzle in said carrying direction.
 5. A liquidejecting apparatus according to claim 4, wherein, after said sensordetects the edge of said medium, a process of carrying said medium insaid carrying direction using said carry unit and a process of movingsaid head and ejecting the liquid onto said medium are repeated for apredetermined number of times, and then ejection of the liquid onto saidmedium is ended.
 6. A liquid ejecting apparatus according to claim 5,wherein the predetermined number of times is a plural number of times;and wherein the predetermined distance in the process of ejecting theliquid onto said medium is increased in correspondence with an increasein an aggregate carry amount of said medium after the detection of theedge of said medium.
 7. A liquid ejecting apparatus according to claim6, wherein said predetermined distance is a value obtained bysubtracting a predetermined amount from said aggregate carry amount. 8.A liquid ejecting apparatus according to claim 7, wherein, the higherthe precision of detection with which the edge of said medium isdetected is, the smaller said predetermined amount is made.
 9. A liquidejecting apparatus according to claim 2, wherein the edge of said mediumis detected by determining whether or not the edge of said medium hadpassed a predetermining position in said carrying direction.
 10. Aliquid ejecting apparatus according to claim 9, wherein said liquidejecting apparatus further comprises a medium-supporting section forsupporting said medium; wherein said sensor is provided with alight-emitting section for emitting light toward said medium-supportingsection, and a light-receiving section for receiving the light that hasbeen emitted from said light-emitting section; and wherein, bydetermining, based on an output value of said light-receiving section,whether or not said medium is in a traveling direction of the lightemitted from said light-emitting section, it is determined whether ornot said edge had passed the predetermined position in said carryingdirection.
 11. A liquid ejecting apparatus according to claim 10,wherein the light is emitted from said light-emitting section toward aplurality of positions different from one another in a direction ofmovement of said head; and wherein, based on the output value of saidlight-receiving section that has received the emitted light, it isdetermined whether or not said medium is in said traveling direction ofthe light.
 12. A liquid ejecting apparatus according to claim 11,wherein said sensor is provided in/on a movable moving member; whereinthe light is emitted from said light-emitting section toward saidplurality of positions while moving said moving member; and wherein,based on the output value of said light-receiving section that hasreceived the emitted light, it is determined whether or not said mediumis in said traveling direction of the light.
 13. A liquid ejectingapparatus according to claim 12, wherein said head is provided in/onsaid moving member; and wherein, while moving said moving member, thelight is emitted from said light-emitting section toward said pluralityof positions, based on the output value of said light-receiving sensorthat has received the emitted light, it is determined whether or notsaid medium is in said traveling direction of the light, and the liquidis ejected from said nozzles provided in said head.
 14. A liquidejecting apparatus according to claim 2, wherein said liquid is ejectedwith respect to an entire surface of said medium.
 15. A liquid ejectingapparatus according to claim 2, wherein said liquid is ink; and whereinsaid liquid ejecting apparatus is a printing apparatus that prints on amedium to be printed, which serves as said medium, by ejecting the inkfrom said nozzles.
 16. A liquid ejecting apparatus comprising: a movablehead that is provided with a plurality of nozzles for ejecting an ink; acarry unit for carrying a medium to be printed in a predeterminedcarrying direction; and a sensor for detecting an edge of said medium tobe printed; wherein said liquid ejecting apparatus controls ejection ofsaid ink from said plurality of nozzles in accordance with a result ofthe detection of said sensor; wherein, due to a detection error in saidsensor that occurs when said sensor detects the edge of said medium tobe printed, a position of the edge of said medium to be printed whensaid edge is detected fluctuates within a range from a first position toa second position; wherein a position, in said carrying direction, of anozzle located most upstream in said carrying direction, of among saidplurality of nozzles, is in the middle of said first position and saidsecond position; wherein, based on the result of the detection, the inkis kept from being ejected from said nozzle located most upstream insaid carrying direction and nozzles located within a predetermineddistance from that nozzle in said carrying direction; wherein, aftersaid sensor detects the edge of said medium to be printed, a process ofcarrying said medium to be printed in said carrying direction using saidcarry unit and a process of moving said head and ejecting the ink ontosaid medium to be printed are repeated for a predetermined number oftimes, and then ejection of the ink onto said medium to be printed isended; wherein the predetermined number of times is a plural number oftimes; wherein the predetermined distance in the process of ejecting theink onto said medium to be printed is increased in correspondence withan increase in an aggregate carry amount of said medium to be printedafter the detection of the edge of said medium to be printed; whereinsaid predetermined distance is a value obtained by subtracting apredetermined amount from said aggregate carry amount; wherein, thehigher the precision of detection with which the edge of said medium tobe printed is detected is, the smaller said predetermined amount ismade; wherein the edge of said medium to be printed is detected bydetermining whether or not the edge of said medium to be printed hadpassed a predetermining position in said carrying direction; whereinsaid liquid ejecting apparatus further comprises a supporting sectionfor supporting said medium to be printed; wherein said sensor isprovided with a light-emitting section for emitting light toward saidsupporting section, and a light-receiving section for receiving thelight that has been emitted from said light-emitting section; wherein,by determining, based on an output value of said light-receivingsection, whether or not said medium to be printed is in a travelingdirection of the light emitted from said light-emitting section, it isdetermined whether or not said edge had passed the predeterminedposition in said carrying direction; wherein the light is emitted fromsaid light-emitting section toward a plurality of positions differentfrom one another in a direction of movement of said head; wherein, basedon the output value of said light-receiving section that has receivedthe emitted light, it is determined whether or not said medium to beprinted is in said traveling direction of the light; wherein said sensoris provided in/on a movable moving member; wherein the light is emittedfrom said light-emitting section toward said plurality of positionswhile moving said moving member; wherein, based on the output value ofsaid light-receiving section that has received the emitted light, it isdetermined whether or not said medium to be printed is in said travelingdirection of the light; wherein said head is provided in/on said movingmember; wherein, while moving said moving member, the light is emittedfrom said light-emitting section toward said plurality of positions,based on the output value of said light-receiving sensor that hasreceived the emitted light, it is determined whether or not said mediumto be printed is in said traveling direction of the light, and the inkis ejected from said nozzles provided in said head; wherein said ink isejected with respect to an entire surface of said medium to be printed;and wherein said liquid ejecting apparatus is a printing apparatus thatprints on said medium to be printed by ejecting the ink from saidnozzles.
 17. A printing system comprising: a main computer unit; and aliquid ejecting apparatus that is connectable to said main computer unitand that is provided with a movable head that is provided with aplurality of nozzles for ejecting a liquid; a carry unit for carrying amedium in a predetermined carrying direction; and a sensor for detectingan edge of said medium; wherein said liquid ejecting apparatus controlsejection of said liquid from said plurality of nozzles in accordancewith a result of the detection of said sensor; and wherein a position,in the carrying direction, of said sensor is at the same position of oron an upstream side of a nozzle located most upstream in said carryingdirection, of among said plurality of nozzles.
 18. A liquid ejectingapparatus comprising: a movable head that is provided with a pluralityof nozzles for ejecting a liquid; a carry unit for carrying a medium ina predetermined carrying direction; and a sensor for detecting an edgeof said medium and that is movable with said head; wherein said liquidejecting apparatus controls ejection of said liquid from said pluralityof nozzles in accordance with a result of the detection of said sensor;and wherein a position, in the carrying direction, of said sensor is atthe same position of or on an upstream side of a nozzle located mostupstream in said carrying direction, of among said plurality of nozzles.19. A liquid ejecting apparatus comprising: a movable head that isprovided with a plurality of nozzles for ejecting a liquid; a carry unitfor carrying a medium in a predetermined carrying direction; and asensor for detecting an edge of said medium and that is movable withsaid head; wherein said liquid ejecting apparatus controls ejection ofsaid liquid from said plurality of nozzles in accordance with a resultof the detection of said sensor; and wherein a position, in the carryingdirection, of said sensor is on an upstream side of a nozzle locatedmost upstream in said carrying direction, of among said plurality ofnozzles.
 20. A liquid ejecting apparatus according to claim 19, whereinsaid sensor detects a lateral edge of said medium; and wherein saidliquid ejecting apparatus controls ejection of the liquid from saidplurality of nozzles in accordance with a position of the lateral edgeof said medium that has been detected.
 21. A liquid ejecting apparatusaccording to claim 20, wherein a position, on the most downstream sidein said carrying direction, of a detection region of said sensor islocated on the upstream side, in said carrying direction, of said nozzlelocated most upstream in said carrying direction.
 22. A liquid ejectingapparatus according to claim 19, wherein said carry unit carries saidmedium by a predetermined carry amount in said carrying direction; andwherein the position, in the carrying direction, of said sensor is onthe upstream side, in said carrying direction, away from said nozzlelocated most upstream in said carrying direction by more than said carryamount.
 23. A liquid ejecting apparatus according to claim 22, whereinsaid liquid ejecting apparatus ejects the liquid onto the edge of saidmedium using a portion of said plurality of nozzles after said sensor nolonger detects said medium.
 24. A liquid ejecting apparatus according toclaim 23, wherein said liquid ejecting apparatus ejects the liquid ontosaid medium using all of said plurality of nozzles in a state where saidsensor no longer detects said medium, and after said carry unit hasfurther carried said medium by said carry amount, said liquid ejectingapparatus ejects said liquid onto the edge of said medium using aportion of said plurality of nozzles.
 25. A liquid ejecting apparatusaccording to claim 22, wherein a position, on the most downstream sidein said carrying direction, of a detection region of said sensor is onthe upstream side, in said carrying direction, away from said nozzlelocated most upstream in said carrying direction by more than said carryamount.
 26. A liquid ejecting apparatus according to claim 19, whereinsaid carry unit has a carry roller for carrying said medium up to aposition where said liquid can be ejected onto said medium; and whereinthe position, in the carrying direction, of said sensor is on thedownstream side of said carry roller.
 27. A liquid ejecting apparatusaccording to claim 26, wherein a process of correcting a skew in saidmedium is performed on the upstream side of said carry roller.
 28. Aliquid ejecting apparatus according to claim 26, wherein a position, onthe most upstream side in said carrying direction, of a detection regionof said sensor is on the downstream side, in said carrying direction, ofsaid carry roller.
 29. A liquid ejecting apparatus according to claim26, wherein said liquid ejecting apparatus further comprises asupporting section for supporting said medium that is carried from saidcarry roller; and wherein said sensor is arranged such that a detectionregion of said sensor is located on said supporting section.
 30. Aliquid ejecting apparatus according to claim 29, wherein calibration ofsaid sensor is performed based on an output signal of said sensor in astate in which said supporting section is not supporting said medium.31. A liquid ejecting apparatus according to claim 29, wherein aposition, on the most upstream side in said carrying direction, of thedetection region of said sensor is on said supporting section.
 32. Aliquid ejecting apparatus according to claim 29, wherein said carry unitcarries said medium in a slanted manner with respect to said supportingsection; and wherein the position of said sensor is on the downstreamside, in said carrying direction, of a position at which a front edge ofsaid medium first comes into contact with said supporting section.
 33. Aliquid ejecting apparatus according to claim 32, wherein said carry unithas a paper discharge roller for discharging said medium; and whereinsaid medium that has been carried in a slanted manner with respect tosaid supporting section passes a print region within which the liquidejected from said nozzles land, and then reaches said paper dischargeroller.
 34. A liquid ejecting apparatus according to claim 32, wherein aposition, on the most upstream side in said carrying direction, of thedetection region of said sensor is on the downstream side, in saidcarrying direction, of the position at which the front edge of saidmedium first comes into contact with said supporting section.
 35. Aliquid ejecting apparatus according to claim 19, wherein said liquid isink; and wherein said liquid ejecting apparatus is a printing apparatusthat prints on a medium to be printed, which serves as said medium, byejecting the ink from said nozzles.
 36. A liquid ejecting apparatuscomprising: a movable head that is provided with a plurality of nozzlesfor ejecting an ink; a carry unit for carrying a medium to be printed ina predetermined carrying direction; and a sensor for detecting an edgeof said medium to be printed and that is movable with said head; whereinsaid liquid ejecting apparatus controls ejection of said ink from saidplurality of nozzles in accordance with a result of the detection ofsaid sensor; wherein a position, in the carrying direction, of saidsensor is on an upstream side of a nozzle located most upstream in saidcarrying direction, of among said plurality of nozzles; wherein saidsensor detects a lateral edge of said medium to be printed; wherein saidliquid ejecting apparatus controls ejection of the ink from saidplurality of nozzles in accordance with a position of the lateral edgeof said medium to be printed that has been detected; wherein a position,on the most downstream side in said carrying direction, of a detectionregion of said sensor is located on the upstream side, in said carryingdirection, of said nozzle located most upstream in said carryingdirection; wherein said carry unit carries said medium to be printed bya predetermined carry amount in said carrying direction; wherein theposition, in the carrying direction, of said sensor is on the upstreamside, in said carrying direction, away from said nozzle located mostupstream in said carrying direction by more than said carry amount;wherein said liquid ejecting apparatus ejects the ink onto the edge ofsaid medium to be printed using a portion of said plurality of nozzlesafter said sensor no longer detects said medium to be printed; whereinsaid liquid ejecting apparatus ejects the ink onto said medium to beprinted using all of said plurality of nozzles in a state where saidsensor no longer detects said medium to be printed, and after said carryunit has further carried said medium to be printed by said carry amount,said liquid ejecting apparatus ejects said ink onto the edge of saidmedium to be printed using a portion of said plurality of nozzles;wherein the position, on the most downstream side in said carryingdirection, of the detection region of said sensor is on the upstreamside, in said carrying direction, away from said nozzle located mostupstream in said carrying direction by more than said carry amount;wherein said carry unit has a carry roller for carrying said medium tobe printed up to a position where said ink can be ejected onto saidmedium to be printed; wherein the position, in the carrying direction,of said sensor is on the downstream side of said carry roller; wherein aprocess of correcting a skew in said medium to be printed is performedon the upstream side of said carry roller; wherein a position, on themost upstream side in said carrying direction, of the detection regionof said sensor is on the downstream side, in said carrying direction, ofsaid carry roller; wherein said liquid ejecting apparatus furthercomprises a supporting section for supporting said medium to be printedthat is carried from said carry roller; wherein said sensor is arrangedsuch that the detection region of said sensor is located on saidsupporting section; wherein calibration of said sensor is performedbased on an output signal of said sensor in a state in which saidsupporting section is not supporting said medium to be printed; whereinthe position, on the most upstream side in said carrying direction, ofthe detection region of said sensor is on said supporting section;wherein said carry unit carries said medium to be printed in a slantedmanner with respect to said supporting section; wherein the position ofsaid sensor is on the downstream side, in said carrying direction, of aposition at which a front edge of said medium to be printed first comesinto contact with said supporting section; wherein said carry unit has apaper discharge roller for discharging said medium to be printed;wherein said medium to be printed that has been carried in a slantedmanner with respect to said supporting section passes a print regionwithin which the ink ejected from said nozzles land, and then reachessaid paper discharge roller; wherein the position, on the most upstreamside in said carrying direction, of the detection region of said sensoris on the downstream side, in said carrying direction, of the positionat which the front edge of said medium to be printed first comes intocontact with said supporting section; and wherein said liquid ejectingapparatus is a printing apparatus that prints on said medium to beprinted by ejecting the ink from said nozzles.
 37. A printing systemcomprising: a main computer unit; and a liquid ejecting apparatus thatis connectable to said main computer unit and that is provided with amovable head that is provided with a plurality of nozzles for ejecting aliquid; a carry unit for carrying a medium in a predetermined carryingdirection; and a sensor for detecting an edge of said medium and that ismovable with said head; wherein said liquid ejecting apparatus controlsejection of said liquid from said plurality of nozzles in accordancewith a result of the detection of said sensor; and wherein a position,in the carrying direction, of said sensor is on an upstream side of anozzle located most upstream in said carrying direction, of among saidplurality of nozzles.